Yep, and windows can only open around 189 windows or thereabouts, and for some reason mIRC is calling each channel a window and abusing the heap as such making it impossible for many other programs to be run when mIRC is hogging the heap in such a fassion.
(The other mIRC instance only has 13 windows)
So yeh, it rapidly hits that mark, and if it wasn't for mIRC calling everything (chans, status windows, pm's, etc) as window events/heap users such as it is, this wouldn't be that big a problem. For example, I have 100 tabs open in Opera at any given time, and it doesn't cause any other issues with the window-opening limit that Windows seems to have. I can close Opera and I get to open one more chan in mIRC, meaning that Opera only takes up one such element on the heap while mIRC is taking up at least 100 by itself. This makes me think there is a much better way to do it if all the tabs in any other application (browsers, pdf, text editors) still only count as one app on the heap.
--Using WinXP Pro SP3