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Why I disable OpenGL in Photoshop CS5

See yesterday’s discussion on OpenGL problems.

Update: repeated and consisting testing for OpenGL on my 3.33GHz Mac Pro Nehalem shows that it is SLOWER when enabled than when it is disabled, using the diglloydSpeed1 benchmark: 21.7 second vs 22.4 seconds. That’s only 3% slower, but it’s supposed to make things go faster.

One thing I do constantly in Photoshop is to toggle layers and channels for viewing:

  • With OpenGL disabled, screen refresh is instantaneous.
  • With OpenGL enabled in any form, screen redraw is herky-jerky and slow.
OpenGL Advanced Settings
OpenGL Advanced Settings

I do use a 30 inch display, and I don’t know if this issue exists on smaller displays, as I have none smaller.

While I know that OpenGL can speed up some advanced operations (ones I rarely use), the fact that it slows down screen redraw so badly makes it unusable for me.

I can choose OpenGL Basic, Normal, Advanced . The Basic setting is fastest, but still sluggish. The Vertical Sync setting doesn’t matter. It doesn’t matter if I use the NVidia GT120 or the ATI Radeon 4870.

This is not a single machine issue; with an 8-core Mac Pro and a quad-core Mac Pro, same problem. The problem has also existed for well over a year, and with previous Mac OS X versions, and CS4.

At settings other than Basic, it’s even worse: a checkerboard pattern is visible for the better part of a second! See below.

With OpenGL enabled, the redraw is not only so slow I can easily see it sluggishly redraw, I can photograph it too! The refresh takes almost an entire second using OpenGL, but is almost instant with it disabled. At this reduced size, the checkerboard pattern is not visible, but that white area is the checkerboard pattern that Photoshop displays prior to drawing.

Below is what happens in CS5 or CS4 on my Mac Pro Nehalem 8-core 2.93GHz with 48GB memory, SSDs, etc. It’s absurdly poor performance. Here, I switched to viewing RGB to viewing the red channel. A similar problem occurs toggling layers on/off. Performance is erratic, sometimes it takes about 1.5 seconds for the refresh, at other times perhaps 1/2 second.

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