Poor performance (and game crash) during autosave on 1.18 pre-1 [Minecraft Java]

Very strange - seem to be having very poor performance issues with 1.18 pre-1 when it auto saves (and some of the most recent snapshots).

FPS reads fairly healthy in debug screen but I start to experience severe lag spikes / jerk movements, and in some cases, the game crashes. Even on modest render distances such as 16 chunks and a simulation distance of 5 on the fast graphic setting and 50% entity distance. I think I've noticed when the game autosaves, I then experience the spikes... seems to be related (but maybe more generally as well)

I normally play 1.17 on 28 render distance no issue's with fancy graphics, so something is definitely going on with 1.18. I would go as far as saying it's unplayable on my machine which is by no means a bad CPU and G card (pics attached).

Vid showcasing the poor performance on very average render distances: https://drive.google.com/file/d/12NtmE71YaCDfI3WHlxpTl_pzbrLXWBBA/view?usp=sharing