Nice job here, these are looking amazing! Full points for week 2. As it looks like you guys found out, performance is going to be the biggest challenge here. So far the image planes with custom normals approach seems to be the clear winner in terms of performance, but for these background trees it seems that it’s still pretty heavy if there is a lot of them.
For that reason, I really like both 1 and 3 of your above tests, and I’d probably lean towards #3 since it appears to have the fewest amount of image planes. See if you can get it all the way down to three or so planes per tree. You could also try using a technique similar to this since they will all be farther away: How to Fake a Large Scale Forest in Blender / Part 1 (Tutorial EN) – YouTube
