So are you using DreamSNES for your PC? Cause it was actually developed for use with the Sega Dreamcast which could explain the lag if you are using it on your PC. For PC SNES emulation I recommend using either ZSNES or SNES9X. ZSNES is the better of the two in my opinion but some people don't really like it's GUI. Try them both and see which one you like!
I've tried both zsnes and snes9x. Both work pretty good. Not sure if any other games do this, but on zsnes, i can't get the the special circuit on Super Punch-Out. Got to it on snes9x. Can't get to it on the psp, tho.