@brunoara Ok so I'll fill you in with I did
I disabled Superfetch, restarted the pc and it was the same thing, so I enabled it again because that solution was useless, I tried with system maintenance but know what? that thing told me that there were no problems, so, what can I do? because the only solution that makes sense is that a process uses a lot of I/O read, write etc. and Opera GX has multiple processes which all of them uses quite a lot of disk

@brunoara yeah yeah yeah I searched in microsoft forums too, and there were generic responses of the problem, misunderstanding the DISK problem with CPU problem, but seeing the task manager thing was one of the few solutions, disabling superfetch too and now the thing of the troubleshooting, I have my pc pretty clean of unused files, I use Avast Cleanup Premiun and CCleaner too
so maybe I should try disabling superfetch and after that check the system maintenance, if there's not a solution it may be "task manager" thing, someone had the same problem and discovered that a process had a I/O write bytes and read bytes of 700k or so, and when he disabled that process his pc went to normal again

I've had this problem for a few weeks ago that System uses 100% disk every time I startup my computer, and doing some research I found that Opera is the one who makes that issue because uses the most quantity of I/O read I/O write I/O read bytes I/O write bytes
different processes of Opera uses a lot of each one of those
I/O Read 354,000 and still going up I/O write 318,000 and still going up I/O read bytes 480,000 and still going up really fast I/O write bytes 469,000 and still going up too
the 100% disk usage last for 2 minutes or so and thereafter drops back to 0 but it's annoying and I wanna know if this problem may be caused by Opera