There's nothing you can do. Your hardware is the bottleneck and using more ram won't help speed it up. Your hard drive will only extract a bit faster at first, once it reaches it "sustained speed" it will continue at that speed regardless of ram usage. You should do fragmentation on that drive to hopefully boost speeds by a bit. My 8tb western digital hdd does the same. Anything over 10gb being written to itself takes a lot of time. But if you had an additional drive and you extract to the other drive, speeds will significantly be better. Look into getting an ssd.
