Hier sind einige Informationen dazu:
Indy Write Buffering / Efficient TCP communication
* "Write buffering is disabled by default. You can check write buffering to see if it's active in your code by testing the fConnection.IOHandler.
WriteBufferingActive property"
* welchen Wert hat die Property TIdIOHandlerSocket.UseNagle (entspricht TCP_NODELAY option) ?