actually, the layers are not 1024x1024, they are the size of the preview, which for a 1024x768 resolution would be something like 800x700 or so there are 1024x1024 images used for : pixel-level tiles , pixel-level selection, and there will be one for each region Also, a 1024x1024 24bit bitmap would be 3MB Memory usage with 1 map opened: 30MB with 2 maps opened: 40MB My preview was 1088x718 (doh, got a leak somewhere, closed the 2nd and it stayed at 40MB) Also, for the region 1024x1024 images, I'll actually try to make them as big as they need to be, so if a region takes only a 5x5 area, the bitmap will be 5x5, and will be enlarged as needed if the region takes a larger area. So basically, I'm not sure why, but virtual hDC's don't seem to take up memory... Maybe they take memory of the GPU and it doesn't appear in the process? Enlightenment on the subject would be nice. Edit: Just tried some stuff... memory usage only go up as stuff is painted; whatever remains as background color doesn't take any memory, so I'm not worried at all about large memory usage. Only maps with LOTS of stuff will take lots of memory, and that's pretty much normal.