How to fix brush lag in Photoshop CC with a Cintiq 13 HD (on apple's Mavericks OS)?

Question

I bought a Cintiq 13 HD about a month ago and have been using it with Photoshop to do a book cover and to teach concept art at a university.
Everything with Adobe Photoshop was working fine, as far as I can remember/noticed, until this last week or so.
All of a sudden there is a significant amount of brush lag—to the point of Photoshop being completely unusable.
I have spent hours pouring through the web looking for answers, but to no avail.
In Photoshop, however, there is anywhere from a tiny delay to a full 1 second delay—afterwards the brush *usually* catches back up with me.
If I try to jot down a dozen small lines quickly, sometimes Photoshop skips brush strokes altogether, or only puts down one brush stroke "space" or stamp, whatever you call it.
This happens even if I'm using the most basic airbrush with default settings—I'll have a delay, an occasional skipped brush stroke altogether, and an occasional tiny dot where I first started the brush stroke followed by nothing until I lift up the pen and go to the next stroke.
I also use Corel Painter X3 in my work, and there is no lag whatsoever. I jot down a dozen tiny lines as fast as I can and the Cintiq and Corel keep right up with me.
I have tried playing with the GPU and OpenGL to no avail. My GPU drivers are up to date (I'm on a mac, so it's automatic). I've tried changing the Performance Preferences to Basic, Normal, and Advanced (being sure to restart Photoshop each time) without any real solution. (I will say that changing the GPU settings down from Advanced seemed to produce a slightly faster brush stroke in general, but not in the sense that I'm talking about in this post. More of just the regular lag kind of thing that's to be expected.)
I'm on a Mid-2010 Macbook Pro
2.53 GHz Intel Core i5
8 GB Ram
NVIDIA GeForce GT 330M 512 MB graphics card
Using a SSD drive 512 GB free space
OS X 10.9.5
All Adobe products are completely up to date and I've tried reinstalling the Cintiq drivers.
I'm out of ideas.
At my university I'll be teaching my class the basics of vehicle design very soon here, and I would prefer to use Photoshop over Painter for this sort of thing, due to its superior non-painting tools. But I can't paint when my brush strokes randomly don't appear on the screen, or lag so much that I can't see what I'm doing if I'm working quickly.
Thank you for your help.
Bryan Beus

Answer 1

First of all, thank you so much for taking the time to try to help out. It
is much appreciated.
The two things that first come to mind are: I have many friends in the
industry who paint solely in Photoshop and do just fine. My computer is
technically "old," but the specs are still just fine—even the graphics card
is the exact same one that is in the new Cintiq Companions (the all-in-one
computer/cintiq machines).
And, more so, I was painting on it for a few weeks without noticing
anything. A part of me wonders, did I just not notice it until it became
dramatically worse?
I do remember painting fur, which requires making tons of small brush
strokes over an extended period of time, and I don't remember there being
any lag.
By the way, I forgot to mention: I've even tried going into the Performance
preferences and disabling the graphics card altogether. No luck. Still an
issue.
As far as painting at 100%: I do notice an amount of improvement. The one
brush stamp, or space, whatever you call it, issue only happened on the
first brush stroke (every time) and then just once otherwise. The lag was
tremendous—and I compared it to Painter's performance, which had no issues
whatsoever.
I am really hoping to be able to rely on Photoshop more and more, as its
tools for other aspects of image manipulation are far more robust than
Painter's. And the working compatibility with Adobe InDesign, Flash, and
Adobe Media Encoder are sooooooo useful for speeding up the workflow.
Hopefully we can find out what's going wrong.
I'm truly baffled on this one.
Bryan Beus
Artist and Author
www.bryanbeus.com
Sent from my Tardis