Q: WILL MY MAC RUN FASTER ON AN EXTERNAL SSD DRIVE THAN ON THE LOCAL HD DRIVE?
A: Performance is a matter of weakest link. The factors to consider are:
- Speed of the drive
- Speed of the bus connecting drive to machine
- Speed of computer cpu
- Amount of installed RAM versus amount of RAM desired by the system (is virtual Memory being used)
As a general rule, an external SSD will realize better performance than an internal HDD. Benchtesting the two will find an SSD to be 4–20 times faster than HDD.
However, that is on a bench test, testing only the speed of the drive.
The internal bus is faster than the external for most computers. External USB C / Thunderbolt 3 is an exception. This is one reason why using a SSD connected externally won’t give you 20x performance.
But it will usually be 2–4x faster than your internal hdd.