Hi @mu3484343 - I envy your internet speed, very nice! There was a recent post that discussed some of the delays in the sidebar in Sheets which you can find at the following location:
https://community.tiller.com/t/tiller-responsiveness-itself-is-crazy-slow/20699
I believe that the Tiller team is working on ideas to improve it. There are also a couple tips in there about ways to get certain things done a bit faster.