Hey there,
To be honest, i wouldn’t risk going through all the effort to find that it doesn’t work/ is an unstable build of the emulator, however most new images of RetroPie (for example, 2.5 to 2.6) will come with tested emulator updates that are stable> However, if the emulators usually run at a high enough speed, they will usually only receive slight updates.
If you would like to increase performance, over clock your pi higher than the standard clock.
my current clock is:
1050 CPU
500 Ram
550 Gpu
0 Overvolt
i have found it runs stable at these speeds, but im going to start a topic to see if cpu/gpu overclocking is more important for n64 and psx, and to see if i can even under clock some areas to overclock others (eg gpu down for cpu up)
Any Questions, Please Ask!
AJ.

Hey there,
Which ROM folder are you using / which emulator? The ROM folder which has just n64 is the libretro emulation directory, which is a more precise and accurate emulator, but at the cost of (for some reason) the menu / navigation and speed of emulation
the n64mupen64plus folder is the Mupen64plus directory, which is a less accurate emulator, but runs at a much faster rate and is able to show menus (i prefer this one)
Any Questions, Please Ask!
AJ

I would just use win32diskimager and make a backup of your current sd card then run the binary update from the setup script. It updates the emulators and gives you some more functionality such as selecting which emulator you want to launch based on system or rom.