Maybe this will help, from what I read from Adobe in regards to Optimizing Performance in Photoshop this information is found at Optimize performance Photoshop CC . I underlined , bolded and put in italics, the wording related to Tile Size Adjust cache levels Cache basics Photoshop uses image caching to speed up the redrawing of high-resolution documents while you're working on them. You can specify up to eight levels of cached image data and choose one of the four available cache tile sizes. Increasing cache levels improves Photoshop’s responsiveness while you work, although images may take longer to load. The cache tile size determines the amount of data on which Photoshop operates at a time. Bigger tile sizes speed up complex operations, such as sharpening filters. Smaller changes, such as brush strokes, are more responsive with smaller tile sizes. Cache presets Three cache presets are available in the Performance preferences. Choose the one that matches your primary use case/purpose of using Photoshop: Web/UI Design: Choose this option if you use Photoshop primarily for web, app, or screen design. This option is appropriate for documents having numerous layers of low-to-medium pixel dimension assets. Default/Photos: Choose this option if you use Photoshop primarily to retouch or edit moderate-sized images. For example, use this option if you normally edit photos originating from your mobile or digital camera in Photoshop. Huge Pixel Dimensions: Choose this option if you work extensively with heavy documents in Photoshop; for example, panoramas, matte paintings, etc. Cache levels For finer control, specify cache levels manually; the default value is 4. If you use relatively small files—roughly 1 megapixel or 1280 by 1024 pixels—and many layers (50 or more), set Cache Levels to 1 or 2. Setting Cache Levels to 1 disables image caching; only the current screen image is cached. If you use files with larger pixel dimensions—say, 50 megapixels or larger—set Cache Levels higher than 4. Higher cache levels speed up redrawing. I hope that helps
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