RPCS3 storage space

Hi! I'm new to RPCS3 and my first time on a forum as well. I'm able to run my games just fine so far since I have a pretty good PC, but I noticed that may RPCS3 folder's storage space keeps getting bigger and bigger. After around 5 hours of playing, I noticed that there was almost a 3gb increase in the RPCS3's folder storage size. I've played Asura's wrath for 3 hrs and Persona 5 for 2 hrs now and my RPCS3's folder is at 13.5gb total right now (the PS3 games are not there). So my question is, is this because of the "compiling shaders" thing while playing? If so, how much space will each game take up in total by the time they're finished? Any average space? If it is indeed because of the compiling shaders thingy, how much space do you think will my RPCS3 folder have by the end of each game? And how does this compiling thing work anyway? If it did it on one area, does it not do it anymore when you go back there? I hope I'm not violating any rules with this.