Massive Slowdown after install java 64 bit

[Pointman]

my laptop used to run k-on psp game at 30fps (max speed for it) with jpcsp 32bit, but after install java 64, seeing that jpcsp 64 bit run slower than 32bit version, i back with jpcsp 32bit, but for some reason, the game now run only at 15 fps, and every other game i tried only run half as fast as it used to be.
the 64bit version run at 27 fps but it sudden drop to 22 about every 5 second with the same setting as the 32bit one. i have tried uninstall both java 32 bit and 64bit and reinstall java 32bit but the problem still there.

my laptop spec

intel i3 2330M, 2.2 Ghz
ATI radeon 6470M
4GB Ram