Cabal EP8 fps drop

I think it's ep8, where PA/PD system exists. Usually server owner advertises as Ep8 + ep21 content.
[EDIT: Not sure, probably ep 20+]

The bug(sorry I dont know the correct term) is fps drop all the time but when you open left window (example guild window, stat window, craft window) fps jumps up about extra 20 30 40 fps or maybe even more.

I have tried official cabal, in Bloody Ice at max effect with so many people I get good fps but not in this ep8 private server.

I have also tried classic cabal which does not have this PA/PD system, no auto BM2 retarget and manually unequip weapons to cancel BM. This episode gives good high fps.

Please whoever the developers of this episode please fix this.

EDIT: Additional info
From RivaTunerStatisticServer (RTSS) I notice that GPU load(%) goes up when the left window is being opened, which also increases the framerates

Possible. But 99% P Servers are trash and based on the same files. Each New Update makes it more worse. ;)

Try to work on your own files. Start from scratch :p

Sorry, I forgot to mention. I am just a normal player. I don't know anything about making/creating/developing cabal files and server.
And this bug happens in 2 private servers that I play (I don't want to name servers).

This makes me think that the owners probably bought the game files from the same seller.

I love private servers, I just hope that this is something that can be fixed and thus improving gaming experience of us players.