sudden fps decrease in any nds emulator

hi everyone the thing is that i update my laptod to windows 8.1 and many of my programs to new versions as well, among those is windspro, now whenever i try to play any nds game on any nds emulator, the game runs perfect at 100% but after a while without failure the fps suddenly drop making very frustrating to play, at firts i thought it was a configuration issue, but no matter what i do about that, the same thing happens again, but there are some weird things about this problem, first, if you minimize the emulator for some moments and restore it the fps goes back to normal for a few minutes and then once again they drop, the second thing is that when games are running perfectly the emulator consumes around 26% of cpu's power but when fps drops they consume around half ot that, third is that same thing happens when i run wii/gamecube games with dolphin, and fourth i have no problems with any other emulator below these consoles (nes, snes, sega, gba, n64, psone), so far that's all i know, my computer specs are i3 core 2.13ghz, 2gb ddr3 ram, 256 integrated video card, and all drivers updated, if anyone have any idea about this please let me know as soon as you can, there are some games i really want to play in here since i can't get a hand on all consoles :fpalm: