Apps · Moving apps to your fast drive
Will an app run slower from an external drive?
Short answer: It depends on the drive. A fast SSD on USB-C or Thunderbolt usually feels close to the built-in drive; slow drives make launches slower. Move big apps you use occasionally.
It depends on your drive and connection. A fast SSD on a USB-C or Thunderbolt port usually feels much like the built-in drive once an app is open; a slow spinning disk or an older USB connection makes launches noticeably slower.
That's why apps you open many times a day are usually better left on the built-in drive, and big apps you use occasionally are the best ones to move. Storage Studio flags recently used apps with a Caveat for exactly this reason.