Do you have Bigger Tiles?
On computers with > 1 GB RAM, you can optimize Photoshop to take advantage of the RAM in your system and manage memory more efficiently. This plug-in is only useful if you are working with documents of large pixel dimensions (thousands in each direction) and is not recommended if you work with documents containing many layers (>50 pixel layers).
NOTE: Using Bigger Tiles plug-in can reduce the total time taken for most operations but this is at the cost of slower painting and non-smooth drawing of previews while updating.
From the Photoshop CS4 install disc, drop the //<language>/Goodies/Optional plug-
Ins/Extensions/Bigger Tiles plug-in into the //Adobe Photoshop CS4/Plug-ins/Extensions folder and restart Photoshop.
Also works for Photoshop CS2 & CS3!
