diff --git a/thorlcr/activities/nsplitter/thnsplitterslave.cpp b/thorlcr/activities/nsplitter/thnsplitterslave.cpp
index d1d8f2e2e8e..237e47eedae 100644
--- a/thorlcr/activities/nsplitter/thnsplitterslave.cpp
+++ b/thorlcr/activities/nsplitter/thnsplitterslave.cpp
@@ -58,6 +58,9 @@ class CSplitterOutput : public CSimpleInterfaceOf<IStartableEngineRowStream>, pu
     virtual bool isInputOrdered(bool consumerOrdered) const override;
     virtual void setOutputStream(unsigned index, IEngineRowStream *stream) override;
     virtual IStrandJunction *getOutputStreams(CActivityBase &ctx, unsigned idx, PointerArrayOf<IEngineRowStream> &streams, const CThorStrandOptions * consumerOptions, bool consumerOrdered, IOrderedCallbackCollection * orderedCallbacks) override;
+    // queryTotalCycles is used by downstream activities for the purpose of calculating local execute time.
+    // queryTotalCycles should include all time taken in start() and nextRow() methods.
+    // n.b. This totalCycles are not actually reported - it is only used by downstream activities.
     virtual unsigned __int64 queryTotalCycles() const override { return COutputTiming::queryTotalCycles(); }
     virtual unsigned __int64 queryEndCycles() const override { return COutputTiming::queryEndCycles(); }
     virtual unsigned __int64 queryBlockedCycles() const { return COutputTiming::queryBlockedCycles(); }
@@ -77,6 +80,13 @@ class CSplitterOutput : public CSimpleInterfaceOf<IStartableEngineRowStream>, pu
 //
 // NSplitterSlaveActivity
 //
+// Note regarding NSplitterSlaveActivity::COutputTiming methods:
+// - queryTotalCycles in NSplitterSlaveActivity is not used by downstream
+//   activities (like they are in other activities).  Downstream activities
+//   use CSplitterOutput::queryTotalCycles for the purposes of calculating
+//   local execute time
+// - totalCycles in this class is reported as the activity's StTotalExecuteTime
+//   and it is used to calculate & report the StLocalExecuteTime.
 
 class NSplitterSlaveActivity : public CSlaveActivity, implements ISharedSmartBufferCallback
 {
@@ -212,6 +222,7 @@ class NSplitterSlaveActivity : public CSlaveActivity, implements ISharedSmartBuf
         if (!inputPrepared)
         {
             inputPrepared = true;
+            ActivityTimer t(slaveTimerStats, queryTimeActivities());
             try
             {
                 assertex(((unsigned)-1) != connectedOutputCount);
@@ -299,6 +310,7 @@ class NSplitterSlaveActivity : public CSlaveActivity, implements ISharedSmartBuf
     }
     inline const void *nextRow(unsigned outIdx, rowcount_t current)
     {
+        ActivityTimer t(slaveTimerStats, queryTimeActivities());
         if (1 == activeOutputCount) // will be true, if only 1 input connected, or only 1 input was active (others stopped) when it started reading
             return inputStream->nextRow();
         if (recsReady == current && writeAheadException.get())