If you've already read this far into this topic, you're probably not against a little work under the hood to tune Photoshop efficiency. In that case, I have a few more tips for adjusting the balance between performance and RAM usage. The way you want to think about these tips is in terms of how much RAM you've got installed. If you have more than 2GB of RAM installed, you've got enough room to tune for maximum performance. If you have less than 2GB installed, you need to make compromises to avoid slowing down Photoshop. OK, here we go.
Bigger Tiles Plug-in
When you open an image, Photoshop breaks it up into tiles so that the tiles loaded into RAM are only those involving the part of the image you're working on. By default, Photoshop tiles are on the small side so that they're easier to load into available RAM. If you have more than 1GB of RAM, you can enable the Bigger Tiles plug-in. Bigger tiles mean fewer tiles, and moving fewer, bigger tiles is more efficient than moving more, smaller tiles, if you have enough RAM.
To load the Bigger Tiles plug-in:
Photoshop can use a portion of RAM to remember how an image looks at different zoom levels, so that you experience less of a delay each time you zoom in or out on a large layered file. Of course, there isn't enough RAM to cache every possible zoom level, so Photoshop is set to cache six zoom levels by default. If you work with large layered files and aren't short on RAM, you can set Photoshop to use up to eight cache levels. If you want to make more RAM available for other Photoshop operations or you work with small, flattened images, you can lower this value down to one cache level.
To change the number of cache levels: