Hey there, I've got a very simple on join script to auto-join chans/other networks which has worked quite well for about a year, then yesterday when I turned on mIRC and the script executed, causing my computer to become heavily bogged down, and mIRC to hang. Simple operations such as opening the Task Manager (CTRL+Shift+Escape) would take up to 5 minutes.

I have no idea what could be causing this to happen, as I haven't added any new scripts in about 2 weeks, though I did modify one to have a spam timer of 2 mins instead of 10 secs, but I don't see how that could break it, since all I did was put a 2 after the 1.

What I have tried:
Upgrade from 7.15 to 7.17
Uninstall and reinstall

System info:
OS: Win 7 x64 SP1
Mobo: ASUS M4A785TD-V EVO
CPU: AMD Athlon II x4 620
RAM: 2x 2GB OCZ Obsidian
GFX: EVGA GeForce GTX 460 SE

One possibility that I can think of, is that your anti-virus has been updated, and that update is causing a larger load on your processes, especially if your anti-virus is configured to scan upon execution.
I found that this was the case a while back, and since the system isn't as high end as what you are describing, the difference was even more noticeable.