If you are having performance problems with a list containing 1500 items then I would suggest that you might have deeper issues than a need to manage the views/folders etc. Even in WSS 3.0 you should not notice a performance issue until around 2000 items.
You might want to look at what the list is used for, how it is being queried, what views are set up on it, what workflows are actively being used, any customisations (event receivers etc.)
There are many reasons NOT to use folders, for one thing they are not the best way to navigate an information structure as they are one dimensional. Meta-data is a much better way to organize your data.
Having said that if you purely want to reduce your item count you could use a combination of both to very good effect. The metadata gives you findability and the folders will reduce your item count.
There is no 'silver bullet' for performance issues on large lists. You need to to effectively diagnose the root cause of your problem first.