Can Fasm use more cores?
(read from virtudrive0, do the work0 on core0,write to virtudrive0)and(read from virtudrive1, do the work1 on core1,write to virtudrive1)and(read from virtudrive2, do the work2 on core2,write to virtudrive2)and(read from virtudrive3, do the work3 on core3,write to virtudrive3)...
Is this works? (Is this faster?)

There is no native code in fasm to use threading.

But you can have fasm can use more cores if you launch multiple instances of fasm in parallel. You can have one process for each output file.

It might or might not be faster. Try it and see if it helps in your situation.

Picture differ
Write to virtudrive
compress on virtudrive with uha/paq,etc
write the compressed file to hdd,ssd,pendrive,SDcard.

Why fasm? (facepalm)
You need to create threads/processes via winapi for windows. Fasm is assembler not executor.

Speed.

To increase the speed, move the computer to a car/train/plane/rocket.

The fastest computers in the world are now on board the ISS.

https://www.guinnessworldrecords.com/world-records/66135-fastest-spacecraft-speed#:~:text=The%20fastest%20speed%20by%20a,UTC%20on%2020%20November%202021.
The ali spaceships are faster.

Your global mistake you believe the Fasm is some script engine or some very high-level language where solutions decided by their developers. But here you have to do all this things and you are absolutely free to use as many cores as you want.