This warning on the project page for this module worries me- I'm implementing this on a server with around 10k nodes using CCK facets. While the server has spare capacity, we work really hard to keep things efficient, as at peak times the server can become very congested. The strength of faceted search is when sifting through huge numbers of nodes- is there a way to make this more efficient- some kind of caching?
Faceted Search is database-intensive. If your server can barely keep up with your traffic, this package will make things worst. Make sure to benchmark performance before deploying this system on a busy site or on a site with many thousand nodes.