Writing to Disk incredibly slow! 10.9.5

Question

I have a 16GB (45MB/s write) Compact Flash card and am attempting to copy the contents to my internal Fusion Drive but it's unbelievably slow!  It should (normally) take minutes - but it's taking hours?  I did not have these issues just a couple of days ago before updating to 10.9.5.  Any idea what the problem is?

Answer 1

Thanks Linc,
FWIW - This one of the same CF cards I just used in the last few hours on a 10.9.4 MacBook Air i5 1.8GHz and it was fine.  I actually have 4 CF cards totaling about 50GB for the project I'm on.
Because I had made copies of work in progress on the MacBook Air of the cards (via Lightroom which read the data at expected speeds) - I'm now transferring those files onto a little 2.5" portable which is taking about 20 minutes.  The plan is for a work around - to then transfer the datas off the portable onto the 10.9.5  iMac that is still just chugging away on the first card.
Meanwhile.  I have a TM HDD running on the iMac.  Works fine.
I just connected one of my many 3TB externals and it seems snappy enough (reading/opening).
I just connected the 2.5" portable and am transferring the files ~ 20 minutes Finder Copy time.
Short answer - External HDD transfers seem fine.
Next plan - abort the CF card file transfer, restart the iMac and try it again.  Highly unlikely but I'll try a different CF card too.  I'd like to figure out why CF card xfer became so slow as I won't always have the files on another Mac or HDD.
PS - It can't be the card reader because that same reader worked fine on the MacBook Air.