Performance in Photoshop is affected by several factors:

• Allocation of system RAM
• Computer processor speed
• Adequate GPU capability
• Photoshop configuration

Photoshop CS4 gave users more control over efficient configuration of Photoshop and added GPU support. Photoshop CS5 gives users even more options for optimizing Photoshop performance.

(Much of this information comes directly from Adobe. You can see their knowledgebase documentation by clicking here.)

Allocation of System RAM

Support for 64-bit operating systems is a recent development for PCs with a Microsoft Windows OS. Windows XP has very limited support for 64-bits. Vista was the first Microsoft Windows OS with a 64-bit version designed for consumers. Windows 7, like Windows Vista, offers both 32-bit and 64-bit versions.

Users often expect a 64-bit OS will greatly increase operation speed in Photoshop. Some operations will run faster. Some won't. Adobe cautions users to expect 6-12% speed increase for operations.

The big benefit of 64-bits is the ability to work more efficiently with larger files.

If you have run the 32-bit version of Photoshop CS4/CS5 with a 32-bit Windows OS, you've probably noticed that the maximum RAM Photoshop will use is approximately 1.7GB. This will be the case, whether you have 3GB or 4GB of RAM.

Run the 32-bit version of Photoshop CS4/CS5 under 64-bit Windows Vista or Windows 7 and Photoshop can access almost twice as much RAM. Approximately 3.2GB.

When you use the 64-bit version of Photoshop together with a 64-bit version of Windows Vista or Windows 7, Photoshop can use as much RAM as you can load on your machine.

To optimize how Photoshop CS5 uses memory, proceed to the Edit|Preferences menu item. Then select the Performance... submenu item.

If you're familiar with Photoshop CS4 preferences, you'll notice that Photoshop CS5 preferences are similar. Photoshop CS5 just adds some additional options. (One big improvement in Photoshop CS5 is that you can control tile size without resorting to a Photoshop plug-in. It's now part of the Photoshop Preferences dialog.)

Changing the amount of RAM that Photoshop can use is easy. The screen capture below highlights the Memory Usage controls.

Photoshop CS5 offers a suggested range for setting this allocation based on your system OS and available RAM. In this case, the OS was 64-bit Windows 7 with 6GB of RAM. Photoshop CS5 deducts the amount of RAM required for the operating system. (Around 800MB, in this case.) You can allocate any portion of the remainder

If you use a 64-bit OS, you can set Photoshop to use 100% of the available RAM. The Adobe documentation says, this is advisable only if you run Photoshop and no other application at the same time. Just how practical is that advice? Probably, not all that practical at all. If you run Adobe Bridge, for example, it will need RAM. So will your browser. Etc.

Adobe offers a better solution, although it sounds a little more complicated. You need to watch the Efficiency Indicator in Photoshop CS5.  You can find the efficiency indicator from the pop-up menu on the Status Bar of your image or from the Palette Options item on the Info Palette pop-up menu.

If you find that your efficiency indicator is routinely dropping below 90%, you can consider increasing the amount of RAM allocation (in something like 5% increments). Adding RAM and then increasing the allocation will improve performance. Optimizing the swap drive can also help, since a lower efficiency indicator means more swap file access.

Out of Memory Errors

With a 32-bit OS, you are more likely to get out of memory errors when you allocate too much RAM to Photoshop. Setting Photoshop CS5 to use 100% of available RAM with a 32-bit OS is very likely to result in out of memory errors. You should reduce the memory allocation by something like 5-10%. If you still get out of memory errors, repeat until you find an optimal allocation for your system and your typical usage.

Under 64-bit operating system, out of memory errors typically result from the opposite condtion: not enough RAM being allocated to Photoshop. Try increasing the allocation by 5-10% and see if that helps.

Processor Speed, Multiple Processors, Multiple Cores

Faster processors are a help, but it is easy to over-estimate their effect on Photoshop CS5 performance. Efficient RAM allocation and scratch drive configuration will have a larger impact in many cases. When you run actions or scripts on large files (like the TLR sharpening actions and scripts), processor speed can have a substantial impact. Photoshop writes data to the hard disk incrementally when you pause in Photoshop. When you run an action or script, there are no pauses to give Photoshop an opportunity to incrementally write to the disk, so Photoshop writes to the disk while the action/script runs. Increases in processor speed can improve performance of these processes.

Photoshop can take advantage of multiple processors to improve performance. The same with multiple cores. Not all features in Photoshop leverage multiple processors/cores.

GPUs

Photoshop CS5 can use a graphics display card's GPU instead of the computer CPU to speed screen redraw. For Photoshop to do this,, your display card must contain a GPU that supports OpenGL. It also needs enough RAM to support Photoshop's functions (at least 128 MB). Be sure the display driver supports OpenGL 2.0 and Shader Model 3.0.

This ends Part 1 of Optimize Performance of Photoshop CS5. In Part 2, I'll talk more about Photoshop configuration. Part 3 will conclude with a discussion of operating system and hardware configuration.

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