Method to Increase FPS on Low End PCs
Find the setup.ini file in the folder where the game is installed.
Example path: C:\Program Files\Steam\steamapps\common\OESM\setup.ini
Open this file, at line 7 set hidelowfpswarning=1 to hidelowfpswarning=0 and save the file.
When you restart the game, you will see "LOW FPS DETECTED Do you want to improve your performance?" message prompt. If you select "YES" at this window, you will observe a significant increase in performance since all grass, shadows and water etc. in the game will be turned off.
Warning: Change other lines and values at your own risk. Do not forget to backup before.