So, It is viable to create a javascript emulator that will run at full speed? The answer is yes.

Results greater than 100% mean that will work faster than on a real PSP (in theory):

Due to javascript to not have “goto” keyword, it will harder to make it faster, but it is definetively possible to get fullspeed with current hardware.

About rendering speed. jspspemu is using WebGL and the speed is mostly limited by the gpu, so the rendering speed will be similar to other emulators using OpenGL ES.