If your startup disk is a hard disk, as opposed to a solid-state disk (SSD), try using a different hard disk for your primary scratch disk. Photoshop supports up to 64 exabytes of scratch disk space on up to four volumes. If you have more than one hard drive, you can specify additional scratch disks. To improve performance, set the scratch disk to a defragmented hard disk that has plenty of unused space and fast read/write speeds. The bandwidth limits for various ports are as follows: Here are Adobe’s recommendations for setting scratch disk preferences:įor best performance, connect the scratch disks to a compatible port that has the highest bandwidth limit of all the available ports. Note: there is a very short window between clicking the Photoshop icon to launch it and needing to hold down the keyboard shortcut, so get your fingers ready ahead of time! Note: When launching Photoshop, Option-Command (Mac) / Alt-Control (Win) prompts you to choose an additional scratch disk folder. To do this, choose Preferences > Scratch Disks, and select the desired drive from the list.

By default, Photoshop uses the hard drive on which the operating system is installed as the primary scratch disk however you can change and/or add additional drives for Photoshop to use.

Photoshop will first try to perform the calculations using RAM, but if it runs out of RAM, Photoshop will need to perform the calculations on a “scratch disk”.

As changes are made to documents, Photoshop needs space to make the necessary calculations.

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