Photoshop :: CS6 - Wacom Cintiq / Intuos4 - Pen Drawing Lag

I consider myself to be an advanced Photoshop and computer user. I have worked with Photoshop for several years on a daily basis as a concept and texture artist.

Whenever I draw in Photoshop on either my Cintiq or Intuos4 I experience some rendering lag of my brush strokes. I can draw a line and it takes sometimes about 1 second for it to appear on the screen. The problem is quite frequent and appears on a regular basis. It is quite an annoyance since it kills the illusion of drawing on "paper" and hinders me somewhat from being creative since I have to think of how I draw rather than having my pen being an extension of myself. I have tried everything from resetting Photoshop back to default by holding down CTRL+ALT+SHIFT before startup, but the problem did not disappear. I have also tried to increase and decrease the performance settings under preferences, but it had no positive effect. All my software's and drivers are uptodate and I have consulted Wacom about this issue as well and they say it cannot have anything to do with the drivers since they haven't heard of this issue before. It cannot have anything to do with that the brush I am using is too heavy and is therefore slow to render because even the most basic brushes are slow at times.
 
I usually work on bigger files with a pixel dimension of 3840x2160@300dpi to 5760x3240@300dpi. I have used the same dimensions for years but never had a problem on for example my laptop, which has only a Dual Core Processor with 4 GB Ram, the only thing the laptop has going for it is the graphics card which is a Nvidia Quadro card. But since it is about 4½ years old, I do not think it is any better than my current graphics card which I have in my stationary PC.
 
Software Specs:
 
Operating System: Windows 7
Photoshop CS6
DirectX runtime version: 11
Graphics Card Drivers
Wacom Drivers
 
Everything listed above is up-to-date!
 
Hardware Specs:
 
Processor: Intel Core i7-2600k @ 3.40GHz
Ram: 12 GB
Main Local Harddrive (C: ) (Photoshop installation): Corsair Force GT 240 GB (Read: 555MB/s, Write: 525MB/s)
Photoshop Scratchdisk Harddrive (E: ) : Corsair Performance3 SSD 128 GB (Read: 480 MB/s, Write: 320 MB/s)
Graphics Card: GeForce GTX 460
 
Photoshop Settings Performance:
 
Memory Usage: 90% - (Had on lower but increased to see if it would have any positive effect, but alas, the problem still remains)
History & Cache: History States: 99, Cache Levels: 4, Chache Tile Seize: 1024k - (I tested resetting History States to 25 (Default) but it did not solve the problem)

Scratch Disk: Corsair Performance3 SSD 128 GB (Read: 480 MB/s, Write: 320 MB/s) - (Had it on C: but did not solve the problem) Graphics Processor Settings: Advanced > Active: Use Graphics Processor to Accelerate Computation, Use OpenCL, Anti-alias Guides and Paths. Not Active: 30 bit Display.