Very often I’m working with large sized files that have a lot of layers and consume most of my pc’s RAM. It is also very common for some filters and plugins not to work due to lack of memory.
Here are a couple of tricks to do when this happens:
1. If you’re sure that you’re ok with your work and don’t need your history levels anymore, go to: Edit > Purge > All
If the filter still refuses to work, save your image, exit and restart Photoshop, load up your image again and try the filter now.
If you see no luck again, then you’ll definitely need more memory with that file, which only means bad news if you’ve already reached the 2GB limit of RAM on 32bit XP based machines 😦
Another tip I can give you on saving RAM for your work is to avoid using the copy / paste command (Ctrl+C – Ctrl+V).
Data stored to the clipboard consume RAM space.
Instead use the Alt+Drag combination: with the Move Tool (V) press alt and drag your selection to create a copy of it.
Also to copy whole layers use the duplicate layer command (Ctrl+J) – or right click on the layer in the layers palette and select Duplicate Layer.
Click here to read a post where I cover more aspects on how to make your machine more efficient for Photoshop use.