Ah yeah, flood check.
Note also that mIRC has flood check of its own, which could be enabled on your client, which would slow down the message itself (would explain the copy pasting method)
Edit: the FLOOCHECK is sent by mIRC, not the server, I think this was added recently, that causes a small slow down since mIRC handles it before processing the sending of your messages.
However I can't seem to get mIRC to send that to the IRC server with my test.
Edit2: Ok I can get mIRC to send that by setting the Flood option Queue: own message
Aha! Thank you, didnt notice it was my mIRC sending the flood check just assumed that would be on the server side. But yes issue is all fixed now by just turning that off
