Photoshop uses image caching to speed redrawing of high-resolution images. With caching, Photoshop uses low-resolution versions of images to quickly update the image onscreen. The Cache Levels option allows you to tell Photoshop to save one through eight levels of cached image data. The more cache levels you have, the slower Photoshop opens the file, but the more responsive it is while you work. The fewer cache levels you have, the faster the image loads, but the slower Photoshop performs.
The default Cache Levels setting is 4. However, you can change that depending on the types of files you work with and how much RAM you have.
If you use relatively small files—roughly 1 megapixel or 1280 by 1024 pixels—and many (50+) layers, set the cache to 1 or 2. Setting Cache Levels to 1 disables image caching; only the current screen image is cached.
Note: Some features in Photoshop don't produce the highest-quality result if Cache Levels is 1.
If you use files with larger pixel dimensions—say, 50 megapixels or larger—set Cache Levels higher than 4. Setting a higher cache level improves performance by speeding redraw times.
The cache tile size is the amount of data (tiles) that Photoshop operates on at one time. Photoshop processes each tile of data, then redraws it. Photoshop is more efficient when it operates on larger tiles, but larger tile sizes take longer to redraw. Bigger tiles make complex operations such as sharpening filters go faster. However, smaller changes such as brush strokes are more responsive when Photoshop uses smaller tiles.
In Photoshop CS4, you can change the cache tile size using the Bigger Tiles optional plug-in (see Bigger Tiles plug-in (Photoshop CS4).
In Photoshop CS5 and CS6, you can choose a tile size from the Cache Tile Size pop-up menu in Performance preferences. If you have an Intel "Core" processor, choose 128 K or 1024 K. If your processor is an Intel Pentium 4 or AMD, Photoshop is more efficient using 132 K or 1032 K.
In Photoshop CS5 and CS6, the History & Cache section of the Performance preferences also has three cache presets: Tall And Thin, Default, and Big And Flat. These options set your cache level and tile size based on the kind of document you’re editing and the amount of RAM you have.
- Tall And Thin
- Big And Flat
- Default For images in between.