alexi - usng the db cache gives you more whistles and belles (ie real time exclusion of links that have expired) however it requires a query to be called. Not using the query means that the datastore cache is used. You get the same basic functionality but not so many of the whistles and bells.
To be honest, The extra query isnt much of an overhead.
Pigsy - I appreciate whate you are saying and yes, the more replacements... the more server load. Even with a js callback, your server will need to scan the text for matches you have wich I doubt will lighten your load much. Personally, I never envisioned people using it with 190 replacements! If you come up with a different method, I would love to hear about it for the next release.
Cheers all!
(BTW - just an FYI - Im not around much right now as I am in Spain on holiday with the family. In fact, my wife is going to go nuts if she sees me on the system!... Be back soon

)