strCommand == "tx": ignore until initial block download is complete.
Why? No need to process new transactions that would go in the new block that is being generated when you do not have the entire chain. This would save some CPU cycles and some debug log length.
In my suggested change (C#), I add the initial block download check after adding the CInv to the node's inventory:
CInv inv = new CInv(ppszTypeName.tx, tx.GetHash());
pfrom.AddInventoryKnown(inv);
+ if (CBlock.IsInitialBlockDownload() || CTransaction.IsOrphanTX(tx.GetHash()))
return true;
bool fMissingInputs = false;
if (tx.AcceptToMemoryPool(true, ref fMissingInputs))...
