A lot may depend on what you are using Photoshop for. If you are only creating small 72dpi graphics files for use on the web, then many of the following suggestions may not be necessary. However, if you regularly apply a lot of filters to multi-layered print ready Photoshop files, then the following may be food for thought.
A fast computer seems almost too obvious a suggestion. But if maximum Photoshop performance is what you are after, then a fast processor is probably top of the list. Many Photoshop power users also recommend dual processor solutions, to get the maximum speed benefits.
RAM Memory and lots of it. Photoshop loves memory and, up to a point, you can't have too much. Although, depending on the version of Photoshop, there are suggestions that having over 4GB of RAM doesn't offer any significant speed improvements.
A fast scratch disk. Preferably a completely separate hard disk with no other files on it. Once Photoshop has used up all the available RAM, it will start writing to the hard disk. Having a fast dedicated hard disk to use as scratch disk ensures that Photoshop always has continuous available space to use as swap space. Something that a computer system startup disk may not have. Portable computer users in particular, may want to utilize an external hard drive as a swap disk, as the internal disks in most portables are not very fast.
If you have enough RAM memory, it may be worth going into the Preferences and selecting Memory & Image Cache. Then set the Maximum memory usage to 70%.
If you don't have a lot of RAM, then removing unnecessary plugins and limiting the number of system fonts installed may also help to speed up Photoshop. Reducing the number of history states will also save memory usage.
Learn as many keyboard shortcuts as possible. Learning to use the hotkeys and contextual menus can save lots of time. For example, on a Mac, holding down the Command and Ctrl keys and clicking (or right clicking on the mouse), allows you to move down between layers really quickly. (You do need to click on a non-transparent part of the intended layer).
Navigating complex montages in Photoshop will be much easier if you use the layer groups feature. Giving all groups and layers logical names may also be a major time saver.
from : desaintalkboard