Very slow code completions in Unity project

Hello,

Rider is very good piece of software. Like all apps from JetBrains :-) But one thing is very annoying making it almost impossible to use Rider in my Unity project - the code completions is extremely slow. Of course I checked it when whole solution was already inspected and synchronized with Unity. It is about 3 seconds after writing dot to show up list of completions:

What is interesting, completions with static fields and methods - after writing class name are working normally

Is there any way to inspect what is taking so long? Maybe Rider has problem with some particular file to parse? Thank you in advance!