is there any proof that corrupted registry cause fps drops in game ?

Uh... you've got a lot more to worry about than some FPS drops in games if you have a corrupted registry...

And how do you know your registry is corrupted?

Currently it is fine, but i heard if you have even one freeze, it can permanently corrupt registry, that even dism cannot repair it. I had fps drops after freeze some time and dism repaired it fortunately and than it stopped and i don't think it was by anything else, i have no overheating, or had any other problems at that time. I just wanted some proof. I am not registry expert so i have no idea. Google found nothing about it.

What you "heard" is complete nonsense and you are unnecessarily worrying about a problem that does not exist. A system freeze will never corrupt your registry.

But does it cause fps drops in games. Let say you have corrupted registry. How does it affect gaming performance exactly ?

It is best not to Google around for solutions to some 'problems' without a very high degree of selectivity, as what you get back is a high proportion of rubbish results as regards junk software/applications and spurious claims about System/Registry cleaners that supposedly solve every known problem.
One of those is Registry faults/corruption causing all sorts of fanciful things, amongst which is fps drops which gamers might latch on to.

All this is basically rubbish pseudo analysis to sell you a junk application.

"Let say you have corrupted registry. How does it affect gaming performance exactly ? "

There are millions of entries and links within the Registry, these are all related to Windows and installed applications. You just won't know where or if there is anything wrong.

I test my PC/Laptop with a gamer type benchmark and record the results, then test after each Windows 10 version upgrade. The results have been constant for 6 years despite various changing installs of applications over those years and even back to Windows 8.1. All those changes will have left dead registry entries etc but it has no effect they are not used.

Freezes take many forms with different causes and results. Registry corruption is one of those possibilities. Possible but not at all common.

The results of registry corruption are unpredictable. It is within the realm of possibilities that it would cause a drop in game FPS. I won't waste my time trying to explain how.

Preoccupation with unlikely possibilities is a distraction from more likely possibilities and is a waste of time.