Your SSD is too full, which really can slow reads and writes. Is it a brand that has a toolbox like Intel or Samsung? If so, run a manual TRIM. If not, leave it on long enough to do a TRIM.
Next optimize that SSD -- turn off system restore and delete all restore points, turn off hibernation, and move your paging file to a HDD and none on the SSD. Then don't fill that space, give your SSD a little breathing room.