After dying with an inventory that has items and the grave spawning, the fps will drop, even after picking the grave up the fps will not return.
Steps to reproduce:
Be on version 1.18.2
Die in survival with at least one item in inventory
Have your grave be spawned
Break/collect the grave, and it dissapearing
issue pesists
Expected Result: No fps drop
Actual Result:Fps tanks semi-permanentally, other worlds and even multiplayer sessions have the issue persists
Only way to repair the issue: Exit and close the mc instance and start the game again.

I don't think there's any way for me to find the cuase for this issue without more info. You could try to install spark (mod) and run a profiler or something. I'm not sure exactly how that mod works so I don't know what you need to do, but I think the profile will be able to tell where and why there's lag.

I didn't mean spark would fix the issue, but a spark profile could identify where the lag is coming from (might be wrong but it's the best idea I've got)