If you want something faster than an external hard drive, and better than a USB Flash drive, you can build an external SSD drive with an SSD and an enclosure. I built a 256GB USB 3.1 external SSD for less than $70 that works great on my Mac. Learn how to build your own.
Updated video for November 2022.
Here are 10 ways you can speed up a slow Mac. There's no reason to put up with your Mac being slow. Often this is caused by an app or background process using too many resources, the lack of free hard drive space, a failing drive, or many other reasons.