FPS (Frame Per Second) means that how much frame (image) is being send every second. Sometimes you will see in emulation that it could be: 20fps, 30fps or 60fps. So pretty much, if a game goes to 60fps that means that the game is running really smooth.
But you are saying that there's a fps lag, we'll it's called that the emulator isn't fast. Don't worry it's completely normal. The dev (devollopers) are working at their best for making this really fast. And if you want to make the emulator faster click on a rom, you will see Rom Preference and Advanced Options. Click on one of those and you will see some things enabled. Well I won't need to explain since Corn already explained everything: viewtopic.php?p=28834#p28834
. Ya so pretty much enable the speed ups, but they might make some games unstable.
Now that's called frezze or crash.
Frezze: The game will stop and will force to restart the PSP or the game.
Crash: The game will stop because of instability or of misreading codes.
Well this explains everything so Welcome to Daedalusx64 forum.
PS Make sure to download latest reviews makes more improvements: viewtopic.php?p=44021&f=1#p44021