Some Real Help
Okay, first off, your computer is not slow. I can run Majora's Mask on my Athlon 500mhz without too much lag. However, you have to do some tricks if you want to keep the speed high. Here's some for starters:
1) Windows 98 is horrendous at allocating resources compared to Windows XP Pro. If you've got an Athlon processor, go ahead and make the upgrade. It's well worth it. Just make sure you get the patches with it.
2) Close all other programs running. In Windows 98, this means pressing CTRL+ALT+DEL and "End Task"-ing all the programs open except for Rnaap, Systray, Explorer, and any programs that you know you need open. This should help get rid of processor hogs.
3) Turn off the audio plugin or decrease the quality. The audio plugin is nice, but it puts a lot of strain on the computer.
4) If it's still running slow, try turning off some of the more advanced graphic features in the graphics plugin or in the ROM file settings. Be careful that you don't bring down the RAM expansion to the normal 4MB, though, or Donkey Kong won't work.
5) If worse comes to worse, you can try using a hidden Windows feature. Download an advanced task manager and increase the base priority of Project64 to ABOVE or REALTIME. Be especially careful with this, though, because if you give it too much when it's doing a grueling calculation or when it's frozen, it can throw your system into a nasty crash.
Good luck!
MNGoldenEagle
~500mhZ AMD Athlon
526MB RAM
NVidia Riva TNT2 16MB Graphics Adapter
Creative Sound Blaster 16 AWE32
Windows XP Professional
Dazzle* Video Capture Adapter