World Composition tile boundary performance issue

Hello,

I have a bit of an issue on a map I’ve been working on for a client; I’ve been tearing my hair out for a couple of weeks on this, and have run out of ideas for what may be going on and why. Figured I would post here and see if anyone has any suggestions.

The map is done with world composition, 4 x 4 grid with tiles of 2km squared. It’s a graphically pretty heavy map, but with a lot of tweaking has been brought to an acceptable level of performance in general outside of this specific issue. However, at tile boundaries I am seeing some enormous spikes on the game thread, which after some profiling I have narrowed down to two major culprits; destruction of physics actors on an unloaded tile, and a task called TickAsyncLoadingGT.
The instanced foliage static mesh for the tile being referenced in the screenshot contains about 240,000 instances, which is obviously quite a lot. As stated earlier, GPU load for this has been brought to an acceptable level.

As you can see from the screenshot, the spike on the game thread is pretty spectacular in both cases, especially so in the physics destruction task. Does this seem abnormal? If expected, is there anything I can do to reduce the hitching this causes? I’ve tried playing with just about every relevant project setting under Physics and Streaming, and nothing seems to help.

As a last resort I can try reducing the tile size, but as this entails quite a bit of extra work and introduces a good deal of extra complexity to managing the map for the client, I wanted to get some input as to whether this would be expected behaviour or not with my current setup, and whether there is anything else I could do to try and resolve things before going down that route.

If anyone has any input on this, it would be much appreciated!

As a reference, my PC specs are:
CPU: i9 9900k
GPU: RTX 2080 Ti
RAM: 64gb