Why is my Mac is super slow with removable hard drive plugged in?

Question

I have all our photos on our 1tb HD and every time I plug it in I get the spinning pinwheel for any task. Help!!

Answer 1

Could be the OS X is trying to keep an updated index of files and folders, of that hard drive. You may have to look into the settings to stop external drives from being indexed by 'spotlight' search. There may be other reasons why the lag occurs, in that the drive is relatively huge and it is a hard disk drive, not a flash or SSD where the information is stored, retrieved differently, and at much faster speeds than a HDD.
You could read up on how to stop the external drive from being indexed, or how to have it ignored by the computer's operating system. An example follows, but not necessarily an exact method: http://osxdaily.com/2011/12/30/exclude-drives-or-folders-from-spotlight-index-ma c-os-x/  Or maybe it just isn't indexing correctly and needs some other action, see this example: https://discussions.apple.com/message/23831185#23831185 where ivan says: "read in another discussion the solution, go to Spotlight preferences and into Privacy add your hardrive to the list where you don't want Spotlight search, then remove it, and Spotlight would begin the correct index and stated a time."
What is the spin rate of the external drive in question? Is that a 7500RPM drive? The buffer or cache size may not be as important for a non-boot hard drive when compared to the purposefulness that could perform for an OS X in pre-loading files for a specific purpose, such as to run an application or perform one task.
What kind of enclosure do you have the drive in? Sometimes the drive may be a little slower because of how it is accessed, and if the computer and enclosure both support a higher-speed connectivity, that's best.
The spinning wheel usually represents CPU activity, but that could also mean pending action while the files get found and transferred, since the internal HDD where the system lives also has to spin-up for the OS X to function, move temp files, & virtual memory space on the System's HDD is read and written too, all the while.
So you could look into Activity Monitor to see if some of that spinning wheel is due to the computer and what exactly, relative to files, activity, CPU, RAM, virtual memory, etc is going on. Or some of it, anyway.
Good luck & happy computing!
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