diff --git a/src/net_processing.cpp b/src/net_processing.cpp
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1994,11 +1994,15 @@
     {
         LOCK(cs_main);
 
+        // Process as many TX items from the front of the getdata queue as
+        // possible, since they're common and it's efficient to batch process
+        // them.
         while (it != pfrom.vRecvGetData.end() && it->type == MSG_TX) {
             if (interruptMsgProc) {
                 return;
             }
-            // Don't bother if send buffer is too full to respond anyway.
+            // The send buffer provides backpressure. If there's no space in
+            // the buffer, pause processing until the next call.
             if (pfrom.fPauseSend) {
                 break;
             }
@@ -2047,6 +2051,8 @@
         }
     } // release cs_main
 
+    // Only process one BLOCK item per call, since they're uncommon and can be
+    // expensive to process.
     if (it != pfrom.vRecvGetData.end() && !pfrom.fPauseSend) {
         const CInv &inv = *it++;
         if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK ||