Are you using SSL? If you are, it could be the problem.
Yes, all of them SSL. I
kinda remembered that fact after walking away, but I couldn't see my thread to edit that in by then because it was pending approval.
I'm afraid this is due to OpenSSL v3.x which has a much slower SSL_CTX_load_verify_locations() function. After the move to OpenSSL v3.x in mIRC v7.73, the next version, v7.74, changed how this function is called to minimize the slow-down when multiple connections are opened at the same time. However, it is still slower than older versions of OpenSSL, and there will inevitably be a pause, especially since mIRC is a single-threaded application.
Alright, I had this suspicion, and both you/Wims confirmed that. I'll learn to live with it, it's not like it is more often than once a day after boot up.
Thanks!