Title is clear enough. Let's look at my screenshots!
Below is Low scenery, high assets
And this is Highest scenery,
Well, you can notice the low setting has considerable bluriness compared to highest, but it is not that crisp in highest should worth the fps hit.
I am currently running on low-end laptop and I am tweaking my RW5 via RS_Tools' playerprofiles.bin altering. Tried many, many options for optimum performance vs. reasonable quality, and finally decided that there is no valuable difference between low and medium scenery, and highest is not important since low settings are also eye-catching! I don't ever mention about great FPS loss.
Currently I have low terrain and high object textures, which keeps the train as crisp as it looks in real (including interior, all text readable; no need for highest!), and scenery as good as it looks, yet having great FPS improvement from 10s to 20-23 avg. from cabview, sinking to 13 at worst.
Just my 2 cents, if you are suffering from FPS drops (low-ends), yet you don't wanna turn off TSX(TSX-off totally soaks the atmosphere! ) or tweak for higher,without having eye-catching blurriness, you should open Content/PlayerProfiles.bin and alter setting as below.
<DetailTerrainTexture d:type="sInt32">0</DetailTerrainTexture>
<DetailObjectTexture d:type="sInt32">2</DetailObjectTexture>
What do you think?