Illegitima have you tried letting it stay open a while to see if the memory usage continoues to rise? if so its a memory leak in your script I think =|

when it uses 255mb RAM is it compiled as a finished level? if so perhaps its because all the runtime files have to be opened through the one exe file instead of running through the wed(takes ram) and then the gamestudio just allocate stuff from wed thus preview takes less ram?