I know this is old, but the only parts of RDE that impact performance directly are the scripts it comes with, particularly arrest warrant, which made my mid-range gaming PC start lagging in police chases, can be removed without breaking things. The scripts do things like spawn certain cars in places and other non-essential features. There is an indirect performance impact from rendering a lot of vehicles of course, but providing you have a decent GPU it should have the video memory to handle this without running into issues. When I used to play on a laptop I always had problems using RDE vehicles because of a lack of VRAM in my system (integrated AMD graphics).
So yeah tl;dr the scripts it installs are the main thing that affect performance. Delete them and you should be good.