Prices for internal Mac SSD drives are dropping! If your current drive is at more than 80% capacity, you might be experiencing performance issues (this is the usual entry point for SSD problems).
http://bit.ly/2v5G4V6
- 500 GB for $185
- 1,000 GB for $297
- 2,000 GB for $630
I bought the 500GB upgrade over a year ago, I recommend getting the bundle that includes the tool kit. The instructions online are super clear, the process is simple, and when you are done you will have more room inside, and a nice little external drive in a metal case using your old drive.
To do the upgrade you just do a full backup of your Mac to Time Machine, then power down, replace the drive, then restart. Your Mac will look for a startup disk and give you the option to rebuild from a Time Machine backup. Run that and you are good to go!