Unity Editor Low FPS (Unusable)

Hello guys,
here is a really urgent issue I am facing recently that doesn't allow me to work with Unity.
The problem is that while working on a project, unity sometimes (quite often I should say) slows down dramatically to the point that I can't use it anymore.

I will link some screenshots that I have taken (I was out of play mode, I started lagging so I switched to play mode to provide you some info. Note the white text on the top-right; this text pops out every time it starts lagging on every editor window opened).

Update: for some strange reasons when I click and drag the mouse over a window the fps indicator of that window increases and the window becomes more fluid (the other windows still lag). When I release the mouse button it starts to lag again. What the hell is happening? :/

Update 2: Apparently I have some issues with RepaintAllProfilerWindows and Gfx.WaitForPresent

My system configuration:
CPU: Intel i5 8400
Memory: Crucial Ballistix Sport 16GB DDR4
GPU: SAPPHIRE NITRO+ RX 580 Special Edition
Driver: Radeon Software Version 19.1.1
OS: Windows 10 Pro 64, Verion 1803, OS build 17134.523
Monitor: Samsung C24FG73-LC24FG73FQUXEN, FreeSync enabled

Thank you for your help!

 

Ok guys I solved the problem.

The lag was caused by the fps overlay feature of the NZXT CAM program. Basically if you press Shift + O when you are playing a game a fps indicator will pop up (that's the source of the text on my screenshots).

This software thinks that Unity is a game so when I write some text with a capital O in it the overlay pops up and everything lag :/

I know, that's silly...

 

Not a very good FPS indicator if it significantly reduces FPS