diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalPoints.C b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalPoints.C
index 50443ca893..361c64c051 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalPoints.C
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalPoints.C
@@ -487,6 +487,9 @@ void Foam::globalPoints::sendPatchPoints
     const polyBoundaryMesh& patches = mesh_.boundaryMesh();
     const labelPairList& patchInfo = globalTransforms_.patchTransformSign();
 
+    // Reset send/recv information
+    pBufs.clear();
+
     // Information to send:
 
     // The patch face
@@ -499,6 +502,19 @@ void Foam::globalPoints::sendPatchPoints
     DynamicList<labelPairList> allInfo;
 
 
+    // Reduce communication by only sending non-zero data,
+    // but with multiply-connected processor/processor
+    // (eg, processorCyclic) also need to send zero information
+    // to keep things synchronised
+
+    // Has non-zero data sent
+    Map<int> isActiveSend(0);
+
+    if (UPstream::parRun())
+    {
+        isActiveSend.resize(2*min(patches.size(),pBufs.nProcs()));
+    }
+
     forAll(patches, patchi)
     {
         const polyPatch& pp = patches[patchi];
@@ -508,7 +524,7 @@ void Foam::globalPoints::sendPatchPoints
 
         if
         (
-            (Pstream::parRun() && isA<processorPolyPatch>(pp))
+            (UPstream::parRun() && isA<processorPolyPatch>(pp))
          && (mergeSeparated || patchInfo[patchi].first() == -1)
         )
         {
@@ -561,21 +577,32 @@ void Foam::globalPoints::sendPatchPoints
             }
 
 
-            if (!patchFaces.empty())
+            // Send to neighbour
             {
-                // Send to neighbour
+                UOPstream toNbr(nbrProci, pBufs);
+                toNbr << patchFaces << indexInFace << allInfo;
+
+                // Record if send is required (data are non-zero)
+                isActiveSend(nbrProci) |= int(!patchFaces.empty());
+
                 if (debug)
                 {
-                    Pout<< " Sending from " << pp.name() << " to proc:"
+                    Pout<< "Sending from " << pp.name() << " to proc:"
                         << nbrProci << " point information:"
                         << patchFaces.size() << endl;
                 }
-
-                UOPstream toNeighbour(nbrProci, pBufs);
-                toNeighbour << patchFaces << indexInFace << allInfo;
             }
         }
     }
+
+    // Eliminate unnecessary sends
+    forAllConstIters(isActiveSend, iter)
+    {
+        if (!iter.val())
+        {
+            pBufs.clearSend(iter.key());
+        }
+    }
 }
 
 
@@ -606,7 +633,7 @@ void Foam::globalPoints::receivePatchPoints
 
         if
         (
-            (Pstream::parRun() && isA<processorPolyPatch>(pp))
+            (UPstream::parRun() && isA<processorPolyPatch>(pp))
          && (mergeSeparated || patchInfo[patchi].first() == -1)
         )
         {
@@ -615,6 +642,7 @@ void Foam::globalPoints::receivePatchPoints
 
             if (!pBufs.recvDataCount(nbrProci))
             {
+                // Nothing to receive
                 continue;
             }
 
@@ -623,8 +651,8 @@ void Foam::globalPoints::receivePatchPoints
             List<labelPairList> nbrInfo;
 
             {
-                UIPstream fromNeighbour(nbrProci, pBufs);
-                fromNeighbour >> patchFaces >> indexInFace >> nbrInfo;
+                UIPstream fromNbr(nbrProci, pBufs);
+                fromNbr >> patchFaces >> indexInFace >> nbrInfo;
             }
 
             if (debug)
@@ -929,8 +957,6 @@ void Foam::globalPoints::calculateSharedPoints
 
     // Do one exchange iteration to get neighbour points.
     {
-        pBufs.clear();
-
         sendPatchPoints
         (
             mergeSeparated,
@@ -962,8 +988,6 @@ void Foam::globalPoints::calculateSharedPoints
 
     do
     {
-        pBufs.clear();
-
         sendPatchPoints
         (
             mergeSeparated,
diff --git a/src/OpenFOAM/meshes/polyMesh/syncTools/syncToolsTemplates.C b/src/OpenFOAM/meshes/polyMesh/syncTools/syncToolsTemplates.C
index f24116864f..0cd73e8a6a 100644
--- a/src/OpenFOAM/meshes/polyMesh/syncTools/syncToolsTemplates.C
+++ b/src/OpenFOAM/meshes/polyMesh/syncTools/syncToolsTemplates.C
@@ -130,7 +130,15 @@ void Foam::syncTools::syncPointMap
         DynamicList<label> neighbProcs;
         PstreamBuffers pBufs(UPstream::commsTypes::nonBlocking);
 
-        // Send
+        // Sample and send.
+        // Reduce communication by only sending non-zero data,
+        // but with multiply-connected processor/processor
+        // (eg, processorCyclic) also need to send zero information
+        // to keep things synchronised
+
+        // If data needs to be sent
+        Map<int> isActiveSend(2*min(patches.size(),pBufs.nProcs()));
+
         for (const polyPatch& pp : patches)
         {
             const auto* ppp = isA<processorPolyPatch>(pp);
@@ -140,10 +148,10 @@ void Foam::syncTools::syncPointMap
                 const auto& procPatch = *ppp;
                 const label nbrProci = procPatch.neighbProcNo();
 
-                neighbProcs.push_back(nbrProci);
+                // Neighbour connectivity
+                neighbProcs.push_uniq(nbrProci);
 
                 // Get data per patchPoint in neighbouring point numbers.
-
                 const labelList& meshPts = procPatch.meshPoints();
                 const labelList& nbrPts = procPatch.neighbPoints();
 
@@ -161,14 +169,27 @@ void Foam::syncTools::syncPointMap
                     }
                 }
 
-                if (!patchInfo.empty())
+
+                // Send to neighbour
                 {
                     UOPstream toNbr(nbrProci, pBufs);
                     toNbr << patchInfo;
+
+                    // Record if send is required (non-empty data)
+                    isActiveSend(nbrProci) |= int(!patchInfo.empty());
                 }
             }
         }
 
+        // Eliminate unnecessary sends
+        forAllConstIters(isActiveSend, iter)
+        {
+            if (!iter.val())
+            {
+                pBufs.clearSend(iter.key());
+            }
+        }
+
         // Limit exchange to involved procs
         pBufs.finishedNeighbourSends(neighbProcs);
 
@@ -185,6 +206,7 @@ void Foam::syncTools::syncPointMap
 
                 if (!pBufs.recvDataCount(nbrProci))
                 {
+                    // Nothing to receive
                     continue;
                 }
 
@@ -386,7 +408,15 @@ void Foam::syncTools::syncEdgeMap
         DynamicList<label> neighbProcs;
         PstreamBuffers pBufs(UPstream::commsTypes::nonBlocking);
 
-        // Send
+        // Sample and send.
+        // Reduce communication by only sending non-zero data,
+        // but with multiply-connected processor/processor
+        // (eg, processorCyclic) also need to send zero information
+        // to keep things synchronised
+
+        // If data needs to be sent
+        Map<int> isActiveSend(2*min(patches.size(),pBufs.nProcs()));
+
         for (const polyPatch& pp : patches)
         {
             const auto* ppp = isA<processorPolyPatch>(pp);
@@ -396,10 +426,10 @@ void Foam::syncTools::syncEdgeMap
                 const auto& procPatch = *ppp;
                 const label nbrProci = procPatch.neighbProcNo();
 
-                neighbProcs.push_back(nbrProci);
+                // Neighbour connectivity
+                neighbProcs.push_uniq(nbrProci);
 
                 // Get data per patch edge in neighbouring edge.
-
                 const edgeList& edges = procPatch.edges();
                 const labelList& meshPts = procPatch.meshPoints();
                 const labelList& nbrPts = procPatch.neighbPoints();
@@ -419,14 +449,26 @@ void Foam::syncTools::syncEdgeMap
                     }
                 }
 
-                if (!patchInfo.empty())
+                // Send to neighbour
                 {
                     UOPstream toNbr(nbrProci, pBufs);
                     toNbr << patchInfo;
+
+                    // Record if send is required (non-empty data)
+                    isActiveSend(nbrProci) |= int(!patchInfo.empty());
                 }
             }
         }
 
+        // Eliminate unnecessary sends
+        forAllConstIters(isActiveSend, iter)
+        {
+            if (!iter.val())
+            {
+                pBufs.clearSend(iter.key());
+            }
+        }
+
         // Limit exchange to involved procs
         pBufs.finishedNeighbourSends(neighbProcs);
 
@@ -443,6 +485,7 @@ void Foam::syncTools::syncEdgeMap
 
                 if (!pBufs.recvDataCount(nbrProci))
                 {
+                    // Nothing to receive
                     continue;
                 }
 
@@ -1138,7 +1181,8 @@ void Foam::syncTools::syncBoundaryFaceList
                     const auto& procPatch = *ppp;
                     const label nbrProci = procPatch.neighbProcNo();
 
-                    neighbProcs.push_back(nbrProci);
+                    // Neighbour connectivity
+                    neighbProcs.push_uniq(nbrProci);
 
                     const SubList<T> fld
                     (
diff --git a/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C b/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
index c31af3cca9..de5d2dfed0 100644
--- a/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
+++ b/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
@@ -172,24 +172,23 @@ void Foam::fvMeshSubset::doCoupledPatches
 
     label nUncoupled = 0;
 
-    if (syncPar && Pstream::parRun())
+    if (syncPar && UPstream::parRun())
     {
-        PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
+        PstreamBuffers pBufs(UPstream::commsTypes::nonBlocking);
 
         // Send face usage across processor patches
-        for (const polyPatch& pp : oldPatches)
+        if (!nCellsUsingFace.empty())
         {
-            const auto* procPatch = isA<processorPolyPatch>(pp);
-
-            if (procPatch)
+            for (const polyPatch& pp : oldPatches)
             {
-                const label nbrProci = procPatch->neighbProcNo();
+                const auto* procPatch = isA<processorPolyPatch>(pp);
 
-                if (!nCellsUsingFace.empty())
+                if (procPatch)
                 {
-                    UOPstream toNeighbour(nbrProci, pBufs);
+                    const label nbrProci = procPatch->neighbProcNo();
 
-                    toNeighbour <<
+                    UOPstream toNbr(nbrProci, pBufs);
+                    toNbr <<
                         SubList<label>(nCellsUsingFace, pp.size(), pp.start());
                 }
             }
@@ -208,19 +207,18 @@ void Foam::fvMeshSubset::doCoupledPatches
 
                 if (!pBufs.recvDataCount(nbrProci))
                 {
+                    // Nothing to receive
                     continue;
                 }
 
-                UIPstream fromNeighbour(nbrProci, pBufs);
-
-                const labelList nbrList(fromNeighbour);
-
-                // Combine with this side.
-
-                if (!nCellsUsingFace.empty())
+                labelList nbrCellsUsingFace;
                 {
-                    const labelList& nbrCellsUsingFace(nbrList);
+                    UIPstream fromNbr(nbrProci, pBufs);
+                    fromNbr >> nbrCellsUsingFace;
+                }
 
+                if (!nCellsUsingFace.empty() && !nbrCellsUsingFace.empty())
+                {
                     // Combine with this side.
 
                     forAll(pp, i)
diff --git a/src/meshTools/algorithms/MeshWave/FaceCellWave.C b/src/meshTools/algorithms/MeshWave/FaceCellWave.C
index 11bdfed7b5..4f459c172a 100644
--- a/src/meshTools/algorithms/MeshWave/FaceCellWave.C
+++ b/src/meshTools/algorithms/MeshWave/FaceCellWave.C
@@ -532,6 +532,19 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
     // Reset buffers
     pBufs_.clear();
 
+
+    // Information to send:
+    DynamicList<Type> sendFacesInfo;
+    DynamicList<label> sendFaces;
+
+    // Reduce communication by only sending non-zero data,
+    // but with multiply-connected processor/processor
+    // (eg, processorCyclic) also need to send zero information
+    // to keep things synchronised
+
+    // If data needs to be sent
+    Map<int> isActiveSend(2*neighbourProcs.size());
+
     for (const label patchi : procPatches)
     {
         const auto& procPatch =
@@ -539,13 +552,12 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
 
         const label nbrProci = procPatch.neighbProcNo();
 
-        // Allocate buffers
-        label nSendFaces;
-        labelList sendFaces(procPatch.size());
-        List<Type> sendFacesInfo(procPatch.size());
+        // Resize buffers
+        sendFaces.resize_nocopy(procPatch.size());
+        sendFacesInfo.resize_nocopy(procPatch.size());
 
         // Determine which faces changed on current patch
-        nSendFaces = getChangedPatchFaces
+        const label nSendFaces = getChangedPatchFaces
         (
             procPatch,
             0,
@@ -554,6 +566,10 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
             sendFacesInfo
         );
 
+        // Shrink
+        sendFaces.resize(nSendFaces);
+        sendFacesInfo.resize(nSendFaces);
+
         // Adapt wallInfo for leaving domain
         leaveDomain
         (
@@ -563,19 +579,29 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
             sendFacesInfo
         );
 
-        if (nSendFaces)
+        // Send to neighbour
         {
+            UOPstream toNbr(nbrProci, pBufs_);
+            toNbr << sendFaces << sendFacesInfo;
+
+            // Record if send is required (non-empty data)
+            isActiveSend(nbrProci) |= int(!sendFaces.empty());
+
             if (debug & 2)
             {
                 Pout<< " Processor patch " << patchi << ' ' << procPatch.name()
-                    << "  send:" << nSendFaces << " to proc:" << nbrProci
+                    << "  send:" << sendFaces.size() << " to proc:" << nbrProci
                     << endl;
             }
+        }
+    }
 
-            UOPstream os(nbrProci, pBufs_);
-            os
-                << SubList<label>(sendFaces, nSendFaces)
-                << SubList<Type>(sendFacesInfo, nSendFaces);
+    // Eliminate unnecessary sends
+    forAllConstIters(isActiveSend, iter)
+    {
+        if (!iter.val())
+        {
+            pBufs_.clearSend(iter.key());
         }
     }
 
@@ -591,6 +617,7 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
 
         if (!pBufs_.recvDataCount(nbrProci))
         {
+            // Nothing to receive
             continue;
         }
 
@@ -602,6 +629,8 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
             is >> receiveFaces >> receiveFacesInfo;
         }
 
+        const label nReceiveFaces = receiveFaces.size();
+
         if (debug & 2)
         {
             Pout<< " Processor patch " << patchi << ' ' << procPatch.name()
@@ -615,7 +644,7 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
             transform
             (
                 procPatch.forwardT(),
-                receiveFaces.size(),
+                nReceiveFaces,
                 receiveFacesInfo
             );
         }
@@ -624,7 +653,7 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
         enterDomain
         (
             procPatch,
-            receiveFaces.size(),
+            nReceiveFaces,
             receiveFaces,
             receiveFacesInfo
         );
@@ -633,7 +662,7 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
         mergeFaceInfo
         (
             procPatch,
-            receiveFaces.size(),
+            nReceiveFaces,
             receiveFaces,
             receiveFacesInfo
         );
@@ -656,12 +685,11 @@ void Foam::FaceCellWave<Type, TrackingData>::handleCyclicPatches()
             const auto& nbrPatch = cycPatch.neighbPatch();
 
             // Allocate buffers
-            label nReceiveFaces;
             labelList receiveFaces(patch.size());
             List<Type> receiveFacesInfo(patch.size());
 
             // Determine which faces changed
-            nReceiveFaces = getChangedPatchFaces
+            const label nReceiveFaces = getChangedPatchFaces
             (
                 nbrPatch,
                 0,
diff --git a/src/meshTools/algorithms/PointEdgeWave/PointEdgeWave.C b/src/meshTools/algorithms/PointEdgeWave/PointEdgeWave.C
index 02398a72db..c284c27772 100644
--- a/src/meshTools/algorithms/PointEdgeWave/PointEdgeWave.C
+++ b/src/meshTools/algorithms/PointEdgeWave/PointEdgeWave.C
@@ -320,6 +320,15 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
     DynamicList<label> thisPoints;
     DynamicList<label> nbrPoints;
 
+
+    // Reduce communication by only sending non-zero data,
+    // but with multiply-connected processor/processor
+    // (eg, processorCyclic) also need to send zero information
+    // to keep things synchronised
+
+    // If data needs to be sent
+    Map<int> isActiveSend(2*neighbourProcs.size());
+
     for (const label patchi : procPatches)
     {
         const auto& procPatch =
@@ -329,8 +338,10 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
 
         patchInfo.clear();
         patchInfo.reserve(procPatch.nPoints());
+
         thisPoints.clear();
         thisPoints.reserve(procPatch.nPoints());
+
         nbrPoints.clear();
         nbrPoints.reserve(procPatch.nPoints());
 
@@ -350,20 +361,31 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
         // Adapt for leaving domain
         leaveDomain(procPatch, thisPoints, patchInfo);
 
-        if (patchInfo.size())
+        // Send to neighbour
         {
+            UOPstream toNbr(nbrProci, pBufs_);
+            toNbr << nbrPoints << patchInfo;
+
+            // Record if send is required (non-empty data)
+            isActiveSend(nbrProci) |= int(!patchInfo.empty());
+
             //if (debug & 2)
             //{
             //    Pout<< "Processor patch " << patchi << ' ' << procPatch.name()
             //        << "  send:" << patchInfo.size()
             //        << " to proc:" << nbrProci << endl;
             //}
-
-            UOPstream os(nbrProci, pBufs_);
-            os << nbrPoints << patchInfo;
         }
     }
 
+    // Eliminate unnecessary sends
+    forAllConstIters(isActiveSend, iter)
+    {
+        if (!iter.val())
+        {
+            pBufs_.clearSend(iter.key());
+        }
+    }
 
     // Finished sends
     pBufs_.finishedNeighbourSends(neighbourProcs);
@@ -382,6 +404,7 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
 
         if (!pBufs_.recvDataCount(nbrProci))
         {
+            // Nothing to receive
             continue;
         }
 
diff --git a/src/transportModels/geometricVoF/advectionSchemes/isoAdvection/isoAdvection.C b/src/transportModels/geometricVoF/advectionSchemes/isoAdvection/isoAdvection.C
index d9b3f75e15..1b54ff2ca1 100644
--- a/src/transportModels/geometricVoF/advectionSchemes/isoAdvection/isoAdvection.C
+++ b/src/transportModels/geometricVoF/advectionSchemes/isoAdvection/isoAdvection.C
@@ -497,7 +497,7 @@ Foam::DynamicList<Foam::label>  Foam::isoAdvection::syncProcPatches
     if (Pstream::parRun())
     {
         DynamicList<label> neighProcs;
-        PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
+        PstreamBuffers pBufs(UPstream::commsTypes::nonBlocking);
 
         // Send
         for (const label patchi : procPatchLabels_)
@@ -506,8 +506,8 @@ Foam::DynamicList<Foam::label>  Foam::isoAdvection::syncProcPatches
                 refCast<const processorPolyPatch>(patches[patchi]);
             const label nbrProci = procPatch.neighbProcNo();
 
-            neighProcs.append(nbrProci);
-            UOPstream toNbr(nbrProci, pBufs);
+            // Neighbour connectivity
+            neighProcs.push_uniq(nbrProci);
 
             const scalarField& pFlux = dVf.boundaryField()[patchi];
             const List<label>& surfCellFacesOnProcPatch =
@@ -519,6 +519,7 @@ Foam::DynamicList<Foam::label>  Foam::isoAdvection::syncProcPatches
                 surfCellFacesOnProcPatch
             );
 
+            UOPstream toNbr(nbrProci, pBufs);
             toNbr << surfCellFacesOnProcPatch << dVfPatch;
         }
 
@@ -533,11 +534,14 @@ Foam::DynamicList<Foam::label>  Foam::isoAdvection::syncProcPatches
                 refCast<const processorPolyPatch>(patches[patchi]);
             const label nbrProci = procPatch.neighbProcNo();
 
-            UIPstream fromNeighb(nbrProci, pBufs);
             List<label> faceIDs;
             List<scalar> nbrdVfs;
 
-            fromNeighb >> faceIDs >> nbrdVfs;
+            {
+                UIPstream fromNbr(nbrProci, pBufs);
+                fromNbr >> faceIDs >> nbrdVfs;
+            }
+
             if (returnSyncedFaces)
             {
                 List<label> syncedFaceI(faceIDs);