Why menu slows down in Ubuntu (on alt or windows buttons)?

Question

ubuntu

The laptop has a weak built-in video card, but after installing ubuntu everything worked fine: I
press the 'windows' key and a menu appears (I don't know what it's called), in which you can enter the name of the application and press enter to start.
This is not too important, since I mainly use the console to launch.
But recently, a similar menu has begun to slow down, which can be called up with the alt key in any application to quickly launch application commands.
Slow* = fadeIn/fadeOut animation takes up to 3 seconds.
no dependence can be traced on the degree of loading of RAM or processor up to exceeding ~ 75% of the loading threshold.
1. Why so?
2. How to fix?
3. And how to call those menus that I spoke about?