That is because the inspect tab checks a lot of things each ticks, it is meant to be like that, try to use the watch values when you can
I was under the impression it all ran all the time, seems I was mistaken :D
Recently I've been trying to reduce all my collision checks as close 0 as possible. And started monitoring the performance of the various sheets, and just now noticed the difference.
Thats quite a huge gap I must say, 30fps or 60fps.
It probably has something to do with all the automated zooming I have on the various layers. (seeing the layer scales number with like 10 decimals spin like crazy)