If you're interested in how the sausage is made, here's a blog post about various tricks and techniques I've used in Gust of Wind to keep the number of shadows, draw calls, dynamic physics objects and the overall number of polygons on screen to a minimum:

[gustofwindgame.com]ːsteamthisː

Pretty much all the points in the post have been in use for a long time, but here's a few optimizations added in this update:

• Terrain details (like rocks and trees) that are far away are more performant and look much better, because I changed them to "impostors" from low-poly meshes
  
• All doors that are not connected to the room player is currently in, are hidden
  
• A bunch of code optimizations
  
• Updating the water plugins used allowed me do improvements like disabling floating scripts from objects that don't currently need them, and disabling the water renderer when not needed (instead of masking it out from the camera)

I used Amplify Impostors plugin to generate "impostor" versions of terrain details, allowing lots of smooth looking rocks and trees with great performance. It's hard to see which rocks are impostors (the ones closer being just regular models of course), but that's what makes them great. The geometry of an impostor is just a plane, but they take their texture by picking the right one from an atlas with lots of views from that rock asset from different directions.
There are some bugfixes as well, but I have a hard time tracking which ones are for bugs that came up with the optimizations, and which ones are actual bugfixes to the previous version. I also worked on the overall flow of the third mission with small changes on some details regarding objectives, making it more enjoyable in my opinion.