PCSX2 settings for smooth gameplay on a mid range pc?

the emulator is mostly cpu bound, so if it's slow, upscaling isn't the first thing to blame. check the fps counter: if it's below full speed even at native resolution, your cpu is the limit and graphics settings won't fix it. if it runs full speed at native, raise internal resolution one step at a time until it stops being smooth, then go back one. and make sure you're on the 2.x builds, the old 1.6 one is a lot slower.