Lag with high count of Instance Static Meshes

Development Asset Creation
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1

We have a project that has a pretty large map, in the map we have some dense forest, for the forest we use Instanced Static Meshes.

We spawn around 300k foliage instances on the map.

All those trees have a collision box because we are allowed to cut them to get wood.

When a tree is cut, there is a lag spike happening that last close to 1 second due to the instance being removed from the list. This seems excessive. Surely there are better ways to handle this ?

If anyone has ideas on how to improve this we would like to hear about it please.

2

Use LoDs for the trees. The higher LoDs won’t need collision.

That should help overall, but I can’t say for certain if that will reduce the lag during instance removal.

Also, are all 300K trees in one group? Maybe break it up into sections.

In this video, the clouds are grouped into a 3x3 grid.

Edit: For LoDs, you’ll need to use Hierarchical Instanced Static Meshes.