ClickUp is slow. When you get good at it, the speed of the app limits your workflow and that's very frustrating.
Here's an example:
When I estimante times for tasks, I click on the estimate button and write something like "5m". After like half a second, I can press "enter" and that sets the estimate. The problem is that little, pesky half a second delay that I have to wait for every single task. The problem is that if I don't, the time estimate will be set to 5 hours even if I wrote "5m".
There are many little things like that (like the cmd+k command) that are annoyingly slow. Sometimes it is faster to navigate manually to a specific task than having to wait for the results to pop up.
They aren't a big issue, they just get frustrating when you really get into the workflow and you're going super fast, but clickup can't keep up.