windows likes to cache files in advance (4GB cached looking at the OP's image), so of that 6 GB, 4 GB is just windows keeping files on hand. Perfectly normal.
I just started my computer and it is reporting 1.7GB cached files and a total of about 4 GB used (inc cache IIRC).
windows makes room if it is needed by removing cached files.
If you want a better general experence, just change some of those programs not to start on start up.
Things like;
Origin
Steam
maybe the Radon video driver interface