Is it true that laptop only has 4 GB of RAM? (It's expandable to 16 GB, if these specs I'm finding are true.) That's pretty low. Photoshop loves RAM, as much as you can muster; if it can't use any available RAM, it's going to use your scratch disk.
As far as storage goes, move anything non-essential off the drive. (This includes, music, photos, documents, etc.) Get a removeable drive or use a NAS (network-attached-storage) solution.
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