This has a background of 512x480 a side panel of 128x480, both blitted without alpha. 4 sprites and 65 DrawObject calls using 32x32 images with alpha. The main area is clipped to 640x480.
It seems to run pretty smoothly, right at about 30 frames per second. I do see a drop from 60 to 30 fps when drawing the 64 image, but this could also be because I am looking through a 144 element array to figure out which locations to draw to. My next test is to change everything to sprites and see if it speeds up any.
Edit: As expected, eliminating the array processing increased the frame rate: