No, and if it does it would be an unnoticeable amount. I've run custom launchers since the Nexus days. If I ever load the stock launcher it's slow to start so that indicates it hasn't been sitting in RAM.

There's so many extra things you can do with custom launchers that I would have a hard time going back. One thing I like about Nova that I haven't seen anywhere else, is folders within icons. So I can make a folder called "Messengers" and put all my different messaging apps in it. I then put Signal as the first in the folder (because I use it most) and in the folder setting select "launch first app" as the tap action and "open folder" as swipe up action. The folder then just becomes a Signal icon and works like a regular Signal icon, but if I swipe up on it, all my different messaging apps come up. Its great and I have these hidden folders for everything. My camera app is actually my gallery, picture editors, etc. My Phone app is also my contacts, meeting app, you get the picture. Keeps my home screen nice and tidy but I still have everything categorized and easy to reach.