I recently found out that keeping Blockland windowed, and in F11 mode, (hosting, if you can) will NEVER crash. Alt-tabbing was the bane of my previous servers, causing much LAG and many crashes. Since I have kept it windowed, it is easy to drift in and out of my server and my work, and others who use my PC dont even notice, as mouseover does not activate, and the mouse can be moved off it just as easily as onto it, and closing other windows leaves you on the desktop, not "::screenflash:: BLOCKLAND! Oh jeez, how do I get back to desktop mode?", a problem I had to fix more than I'd have liked to (My brother and mother both use this PC).
Also, bricks never go 'all grey' as they do when you Alt-Tab for extended periods of time. Also, you dont lag when you bring it into focus, just dont Alt-Tab into it :-)
Also, keep BL in VGA (640x480) mode, anything higher will dran more rescources. And aim into the sky- Less stuff to draw!
Just a quick FYI for thsoe who host without dedicated programs and PCs, which is me while my DARN BROTHER wont give me back my main server PC (He LAN parties at his friends house, and they are in the middle of a serious AOE2 game, apparently!).