“My computer has 60 gigaflops of RAM but Photoshop still can’t handle huge file!”
Finding that Photoshop is not quite running right and making use of the vast amounts of computing power you have stored in that shiny metal box? Hopefully these tips will help out.
Firstly how does Photoshop use the available computer power? A brief look at this will help us better understand how to optimise the system. When Ps is processing your images it will do so using RAM. However, when RAM is in short supply it will have to switch to using any available Hard Drive space (known as scratch disk) to continue working on your image. However, scratch disk space is significantly slower than RAM.
Unfortunately you cannot just put more RAM into the computer and see Ps speed up (also RAM can be expensive.) There are certain limitations Ps has when it comes to how much RAM it can use; which many may not be aware of.
32-bit Photoshop on Windows 32-bit, can only take advantage of 1.7GB of your RAM.
32-bit Photoshop on Windows 64-bit OS, can only take advantage of 3.2GB of your RAM.
64-bit Photoshop on Windows 64-bit OS can use as much RAM as you have.
These only apply to CS4 and CS5. If you are using a Mac, these values differ slightly as the OS is 64-bit. Furthermore, Adobe only released a 32-bit version of CS4, whereas there are 32 and 64-bit versions of CS5.
CS4 Ps on a Mac can only use 3GB of RAM. CS5 (32-bit) can use even less – 2.1GB of RAM. CS5 (64-bit) can use as much RAM as you have.
So thats the end of the RAM guide… or is it? You may have a 64-bit OS and Creative Suite, but Photoshop still isn’t quite running right. Well lets dive into the preferences pane. Open Photoshop and go to Edit > Preferences > Performance (Or Photoshop > Preferences > Performance on a Mac) You will see this brilliant window pop-up:
The main top-left box is the important one. This tells Photoshop how much of the available RAM you will allow it to use. (The available RAM is dictated by the 32/64-bit guide above) In almost all situations you will want Photoshop to make use of everything it can. As previously discussed, RAM is faster than Scratch Disk so what are you waiting for? Drag that slider to the right.
While we are here in the preferences let’s take a quick look at some other optimisations. Take a gander at the top-left box in the panel. There are three options for cache levels. You should use Tall and Thin if you generally edit small, multi-layered images and have not much RAM.Big and Flat is the opposite; large images (potentially hundreds of megapixels) with not as many layers. Default is in between. If you see yourself fitting into one of the extremes, click the button most relevant to your work.
Cache levels are also an interesting optimisation point. Higher cache levels enables Photoshop to store more levels cached image information. This results in slower loading of saved files, but improved performance while actually working on an image. Adobe say that if you are working with images of roughly 1 megapixel then stick to a cache level of 1 or 2. Alternatively; if you work with files of roughly 10 megapixels or more then change the cache levels to above 4.
Cache Tile Size is the amount of data or ’tiles’ that Photoshop can work on at any time. If you have ever been working on a large image and apply a CPU heavy effect, you will probably have seen tiles in action – Photoshop updates and redraws the image as a series of tiles. It works on one at a time and with this preference you can set the size of the tiles. Larger tiles are generally more efficient, especially when it comes to complex effects such as filters like Gaussian blur and sharpening. However, these take longer to re-draw. If you tend to make only smaller changes like painting strokes it is much better to set the tile size lower.
Now press OK and close Photoshop down completely. The changes will take effect the next time you open it.
