I have used Reshade for many years with issue, but in the last few releases at some point I started having MASSIVE drops.
Currently playing Rise of Tomb Raider on a RTX 2080, with minimal things turned on and even on the menu my FPS drops from 155 to 89 when I activate Reshade.
I have had similar drops (although more like 20-30) in other games like The Witcher 3 etc. most games are older games that I should not be having this much of an impact.
I play in 1440p on a 165hz G-Sync monitor. RTX 2080 and a 4790k.
Not sure what the deal is - any ideas or more info I can provide?