That's a terrible idea. `purge` is not a tool for freeing inactive ram. It's a tool for deleting the filesystem cache in order to simulate cold boot conditions for performance analysis. Yes, it has the side effect of reducing memory usage, inasmuch as it's throwing away stuff that was kept in memory. But that doesn't make it an appropriate tool to use.
The downside is it slows filesystem access down across the board until the caches get repopulated. So sure, go ahead and use it if you like having a slow filesystem.
Caches exist for a reason. Deleting them willy-nilly tends to be a bad idea.
From my days of optimizing Firefox startup on the Mac, I remember that this doesn't work 100%. The only way to ensure that caches are 100% purged is to unmount the filesystem.
