For some reason, after exiting GTA V or after playing it for some time, my computer gets super slow, for example if I exit it and have no other processes working, the computer is working on like 5% of the speed it could run on, even opening empty folders on desktop takes 10 or 15+ seconds, which is crazy, because I can run GTA V on medium high settings with good fps, no stuttering, lagging,etc., but after I exit GTA V, regardless whether by going to quit or by killing it in task manager, my computer just slows down entirely.
I can spawn a bunch of modded cars and planes in game that are pretty big in size and the game runs fine, I can drive really fast in the most populated parts of Los Santos and again, no lagging of any sort, so it isn't a lack of RAM that is the issue, but something that happens to it after exiting the game and the only way I can fix it, is by restarting.
Recently I started having some keyboard lagging issues as well, I tell the car to go a little to the left and it keeps on going left even after I let go of the left button and stuff like that. I go to the task manager and it says that I still have almost 1/3 of my RAM free, so I have no idea what could be the problem.
I could buy more RAM (currently I have 4, which may sound little, but I turned of all unnecessary apps and services, so windows uses less than 800mb, which leaves a lot of room for GTA V), the problem with buying more RAM is that the prices have literally doubled since October 2016 when I was upgrading my computer and I don't want to spend that much money now, I'd rather wait a few months for the prices to get normal again.