At the December Web414 meeting I gave a presentation on Prism (Don't call it Webrunner.) Thanks to the instructions on this fine post I did a meta-meta thing on my presentation by installing prism into a fresh virtualization of Ubuntu and using GoogleDocs to show my presentation. You can check out that presentation here. What I didn't have in my presentation was any kind of data about the difference between Prism's system footprint versus FireFox's system footprint.

So, here's a non-scientific comparison of Six Tabs in Firefox vs. Six instances of  Prism all doing basically the same thing. First, I launched and logged in to six instances of prism. One each, running Google Docs, Gmail, Google Reader, Twitter, Last.FM, and Flickr.

And here's the System Resources window.

Then, I launched and opened the same six web sites in tabs in Firefox.

And here's the system resources window in that case:

Summary:

It would appear that reducing your browser's impact on your system is not a significant reason to use Prism. Again, I didn't really study any kind of significant benchmarks beyond these basic screen shots, so if anyone has any scientific data that can prove me wrong, I'd love to see it.  

That doesn't mean, either, than there aren't non-footprint-related reasons to use Prism. Separate processes, easy Desktop integration, reduced UI, and easy deployability are all reasons to put Prism on your machine.

These are all good reasons to encourage Prism's use, but it would appear, unscientifically, that reduced footprint ain't one of them.