You can get good performance on Godot. Mostly this means using GLES2, not going crazy with post-processing effects, and disabling things like real-time shadows. Baked shadows look much better, though are static. Otherwise, the general performance stuff for any 3D app will apply, lower poly models, not crazy resolution textures, optimized code, etc. If none of that helps, you can also run at 720p and just have the window stretch to fill the full screen.
