Help in my PSP 3004 V. 5.03

Help i have a proble in some of my games running in my PSP, like naruto ultimate heroes, when im in the heroes mode then starting it the games always hangs.... and in my Bleach game, when in battle mode the game is soooo very slow and in its menu on the second screen after you hit the start button. the screen always blinking.. What may be the problem with that? in my other adventure game, it is a bit slow. i have a 4 gb memory card and i am using games in my memory...

Is the problem in my memory or just the system itself?