Emulator

Is called GPU so it does some process (Yeah, the graphics that the PC are using but).

Because GPU emulation isn't graphics processing. Very roughly speaking, the GPU receives render instructions from the graphics driver. It can't process application instructions.
Emulating a GPU isn't generating graphics. It emulates every behavior of the real hardware, with more or less accuracy depending on the emulation type. What matters is that emulation is about manipulating data like the original hardware did, and GPU doesn't do that.

For the GPU to do other stuff (like processing physics) the driver must be prepared for that and the application must be coded in order to use that driver capability. Also you can't do that with anything. Among lots of other factors, you need it to be something that can be *heavily* multithreaded, and chip emulation can't.

I kinow that the problem with the speed is mostly because the emulator has to rewrite the instructions so the pc can understand.Yeah I kinda exagerated with the 32 ghz thing,but it was an example.Who knows?Maybe there will be someone that will make a faster jit Hle

I wouldn't say it is impossible, but we've been using Just In Time (JIT) recompilers for more then 10 years, its "invention" (the theory existed, but nobody cared to implement at first) was basically what made N64 emulation at decent speeds possible at the time. This was already done at the cost of accuracy, whatever they do to speed things up may bring glitches and bugs that can't be fixed. RPCS3 is currently HLE'ing the hardware, since we don't need the BIOS for it to run, which should make things a bit more fast and more buggy than LLE. The thing is that it only has an interpreter (which is usually how an emulator starts), which is very, very slow. when it is mature enough, a recompiler of some kind can really speed things, to the point of bringing something all the way up from 3-5 to 20-30 fps (this is just an example).

Thinking now this is kinda funny cause today my PC (specs in the sig) can run N64 games at 60fps on interpreter mode (I just tried it, just change the setting on PJ64), nobody would say that back then, that a computer would be able to interpret N64 games at playable speeds. And that considering PJ64 is single threaded, so it can only use one core for all the emulation work. CPU technology really advanced exponentially in the past decade.