it’s tempting to do when I see progress increase of 0.02 per hour.
I can't think of any reason why shutting down and restarting would improve things.
could it be the block it’s handling at the time?
You can check how long it takes to move up one block.
As for my CPU usage it’s currently below 10% (and the increase per hour is 1.30%)
It could be disk limited too. One way or another, restarting only adds extra work.