When you slow the tick rate down with /tick rate, for example doing /tick rate 1, the speed at which the chat window opens slows down. This may be intentional, but I find it incredibly annoying that when the game is operating at a slower tick rate, trying to type a new command or message in chat often results in the game missing a lot of what I'm typing, due to the fact that the chat box doesn't open up right away. Once the chat window is open however, it receives all my keystrokes like normal.

On a similar note, I find it annoying that a tick rate slower than 20 affects the player at all- specifically the players speed.  When the tick rate is higher than 20, the player moves at normal speed, but when its lower than 20, the player moves in slow-mo. This is obviously intentional, which is great, but it might be nice if the player slow-mo speed only affected survival players for example. If possible, you could also instead make it so that the game tick rate and the player tick rate could be targeted separately.