How much free space does your SSD currently have? You should have ~10-20% free at any given time when using an SSD. If you don't have enough space, either migrate unnecessary data to another drive, or delete data from your SSD.
Depending on your normal computer usage, you could also be utilizing all of you RAM, but i doubt this is the case. However, if you have only 8GB of RAM and you run another OS such as Windows side by side, you may very well have utilized all of your RAM.