Scratch disks

[Superstriker#8]

Will a scratch disk be useful if I only usually work with one file at a time with one or two layers?

 

[mcasan]

Scratch disk is just one area to set for optimum PS performance.

http://helpx.adobe.com/photoshop/kb/optimize-performance-photoshop-cs4-cs5.html

 

[RobWatson]

Depends on how big the file is ...

If you are not running out of RAM then no. Always add more RAM until maxed out.

 

[Timmy]

When using Pshop see how much RAM you're using (e.g. CTRL-ALT-DEL on windows) - if you're maxing it out, buy some more (RAM costs almost nothing nowadays). If you can't add any more RAM and you're still maxing it out - then scratch disks become useful.
They generally work best if it's a separate drive.