Unless you have like 50 channels open at a time, and i mean 50 active channels, not empty ones, ones with at lea 30 people per channel, then its probably not mirc, i would suggest checking your processes with task manager on Windows 2000/Xp and confirming the memory usage. Explorer.exe is very well known for hogging huge amounts of memory, especially when creating thumbs.db for thumbnail icons, and when doing searches and sometimes has not released that memory. Also check for AdWare, as they can intentionally hog memory. Check kazaa if you have it as well. Hoever yes it is possible mirc has a leak, but doubtful. i have an active mirc client running with 6 channels open with an avg of 15 users per channel, and im taking up less than 2mb of ram.
-Cypris