The answer to your question may depend on several aspects. In order to help you it would be useful to know the answers to the questions listed here: FAQ: What information should I provide when posting, or What do you need to know to solve my issue? Also check this FAQ: How do I make Photoshop run faster, or How do I increase performance?
Hi Louise, Because the forum you originally posted in is for beginners trying to learn the basics of Photoshop, I moved your question to the Photoshop General Discussion forum, where you'll get more specialized help.
To help others help you, please reply and provide some additional details: Which operating system and software version are you using?
What does the action contain? What's the size of your images? Certain operations may simply gobble up all memory....