If you refer to the "System Idle" process (in TaskMan or other proccess
monitor) then that means only 2% CPU time is being used. That "Idle"
process is the reverse in that it shows idle use (IOW *not* used), not
consumed cycles as with other proccesses listed.
As to "it is very slow" you may have the wrong group and you certainly
have provided very little information of any use to those reading your
post. Not even the OS, much less any details.