How come that when i play DS games on DeSmuME 0.9.5 its slow?

Can anybody tell me why some games play slow on DeSmuMe?it doesn't seem to play slow whenever I access a menu though.

The menu requires less graphics processing than the game play.
Your computer might not be up to the emulation. Or you may need to try a different emulator. Like No$GBA

Ok thank you. :) oh never mind lol I found out. :D