Those specs are too lazy, so don't expect very nice results. Maybe some tricks will help you. You could improve performance doing this:
VIDEO OPTIONS
Try toggling on/off different values until you found the best results.
-Vertex Cache: The universal option to gain speed boost; work ok with many games.
-Shader: Most times it speed up the game when is enable alone; however, sometimes must be activated with others to notice the speed boost:
Dynamic Shader generation - Decoding of indexed textures (Using CLUT) - Disable UBO
-Only GE Graphics: Certain games need this one in order to show proper graphics; some will break if it is enable as well.
-Saving GE screen to textures instead of memory: Results aren't equal on most games.
-Disable Optimized VertexInfo Reading: This one is weird when bring a speed boost, but games with glitch graphics will fix if it is enable.
COMPILER
Set
MaximumCompilerMethod to 50 or 100; or try the 5 values until you found the best result.
That on JPCSP side; on your machine, if your OS architecture is x64, you may want the x64 build of JPCSP (Latest build here:
http://buildbot.orphis.net/jpcsp/).
If you have Java 6, is better to uninstall it and then install Java 7.
Finally, make sure to update to latest Catalyst which is 12.11 BETA 6.