The DeSmuME emulator is designed for the Nintendo Wii, Windows and Macintosh. It is capable of emulating many different Nintendo DS ROMS and demos. The emulator is far from perfect and is still in the working stages, although it is capable of emulating many ROMs. The DeSmuME emulator focuses more on compatibility of games rather than speed, so there is only so much you can do. This is something to keep in mind when tweaking the DeSmuMe emulator for speed increases.
Enable "Patch DelayLoop SWI" if you have to use an external BIOS image. It is recommended not to use a BIOS image because it slows down the DeSmuME emulator.
Press "A" on "Settings" and switch between OpenGL Renderer and Software Rasterizer. This may improve the speed of the emulator. Press "A" on "Config" and go to "Emulation Settings" and unclick the check mark next to "Enable Bus-Level Timing."
Access the "Sound Settings" and check to use "Dual SPU." Do not set the emulator to use "Advanced SPU Logic" and set "interpolation" to "none." Turning the sound off altogether will increase the speed of the emulator.
Use the DeSmuME builds that are available on the DeSmuMe website. Any other unoffocial "SVN" builds or the NOSSE2 build is not compatible and will be slow.
Enable frame skip by going to "Tools" and clicking on "Frameskipping." Enable framskipping by "1." This will make most games still be able to play. Go to "View," "LCDs Layout" and "One LCD." This will hide the second LCD. This is useful if there is nothing being displayed on the second LCD screen, however it will not speed up the emulator speed. Do not use resize filters or scale the window to any other size than "1x."
Do not use a netbook because they do not have the power to run this emulator. If you are using a laptop or notebook computer, disable the power management. This will allow the computer to run at a better speed. You may also consider purchasing a faster computer or increase your RAM speed by purchasing upgraded RAM cards. It is also wise to install an upgraded CPU. Clean any dust that is blocking your computer fans to allow them to cool your computer better.
Nintendo DS ROMs can be found at numerous ROM websites online such as CoolROM.com, Romhustler.net or DopeROMs.com. See the links in Resources.