Was trying to find an answer for that, tried everything yet issue still persists.

So before I actually write about my issue, I will answer some of your questions:

Q: Bad pc?
A: Hell nah, ryzen5 3600, rx 5600xt, 16gb of ram 3200mhz so it's a roblox issue

Q: Poor internet?

A: As it says in the title, they are "performance" lag spikes, not ping lag spikes. Additionally, my internet is fibre optic, so there's absolutely no way it's caused by wifi (I also switched homes and lag spikes still stayed with me so)

Q: Reinstall roblox/change graphics settings to low?

A: Already tried it few times + installing bloxstrap didn't help + changing graphics settings to low didn't help as well

Q: Anything in logs when pressing F9 after having a lag spike?

A: Absolutely nothing, not even a single error/warning/message

Q: What game?

A: Any game on roblox, and it ONLY happens in roblox, not in any other game.

Q: Format?

A: Didn't help and I am not going to do it for the 2nd time, I got too much important stuff on my current drives

Okay so if I answered all your questions, let's get to the issue:

When playing roblox, I randomly get huge 4-5 seconds lag spike. It is exactly that duration for each one. I have absolutely no idea what is causing it and it started to happen just randomly, can't even remember when.

None of the lag spikes are shorter than 4 seconds or longer than 5, which is extremely weird and frustrating.

The reason why I wrote "performance" and not just performance is because it's not caused by fps or bad hardware, it's just so annoying that I can't even find an answer for that

If anybody got any questions or answers how to fix that annoying issue, please let me know and I will reply asap.