Optimization: don't check the mempool at all if no mempool req ever

src/main.cpp

@@ -4516,7 +4516,7 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                 if (mi != mapRelay.end()) {
                     pfrom->PushMessage(NetMsgType::TX, *mi->second);
                     push = true;
-                } else {
+                } else if (pfrom->timeLastMempoolReq) {
                     auto txinfo = mempool.info(inv.hash);
                     // To protect privacy, do not answer getdata using the mempool when
                     // that TX couldn't have been INVed in reply to a MEMPOOL request.