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Well, the obvious questions are:

Has it always been this way?
If not, when did it start being slow?
What changed between the time it was good and the time was bad?

FWIW, my late 2012 21.5" has a similar pause, although I've never timed it.
 
Well, the obvious questions are:

Has it always been this way?
If not, when did it start being slow?
What changed between the time it was good and the time was bad?

FWIW, my late 2012 21.5" has a similar pause, although I've never timed it.
1. Nope.
2. Probably after the 10.10.2 update. But my other Macs after applying that patch didn't have this problem.
 
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