(Closed)

Falling from 19.95 to 18.23 is not really a particularly bad decrease, and is still a good TPS to be running at. As for why it never stays stable, all servers will change in TPS when they are up, due to factors such as numbers of players online and chunks loaded. If you do want to try and make it higher, which isn't particularly necessary with your TPS, then try removing some of your plugins, 54 is quite a lot to be running.