Not sure if this is even possible with speed tree, I know it looks great and all, but not every tree in the entire game needs to be swaying or moving, could probably cut down on a ton of lag if say only like 20% of the trees have movement.

Also with environmental effects like rain and how a lot of the droplets when they hit the ground and water make that little splash, I know it looks great and all, but you don't really need it. Tweak the environment a little so you can implement the terroforming without lag, I would rather have the game work that see swaying tree or rain droplets ripples.

Maybe the fires don't need that much smoke or fire for that matter, and maybe limit the number of fires in a certain space like only 2 max per 15meters or something like that, you don't need 20 fires in your little camp site.