Unfortunately Celeron CPUs are too slow to handle Chankast. For various reasons Chankast will not run fullspeed on some PCs.
Some demanding games (ie: Dead or Alive) will not run fullspeed on any current machine either.
You can try to run the game fullscreen and overclock or underclock the emulator (read the Chankast manual for more info) but I'm afraid that you can't do much about it...