I've been up to 683 million poly's and it didn't look like that was the limit. If you want your wireframe to load quicker just reduce the object resolution. As for the crashing with 30 trees. If you replicate or drop trees to the ground try doing it in small batches of about 20-30 trees at a time. That is much more stable then moving hundreds at the same time. I've build a scene with 3128 brycian trees once, so it should work.

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