One of the new features of the latest iteration of Adobe Bridge concerns caching. More specifically the feature concerns Bridge's effort to nudge the user to purge the cache frequently. We can assume this is an effort to make Bridge run more smoothly. But this could seriously impact a user's ability to search their image library.
If you go to Bridge Preferences (Command+ or Control+ K) and go to the Cache tab you'll note you can now set Bridge up to purge the cache at a certain point in the future. (By default it is turned off but the number 30 is listed in the "Days" box.).
The temptation would be to turn this on since Adobe recommends frequent or at occasional purging the program's cache. In fact, I've noticed on both my windows and Mac machines a dialogue box will pop up from time-to-time asking if you would like to optimize the cache by "purging stale items." So now Adobe is connecting optimization with purging, that is in and of itself a big shift. If you do purge the cache you will no longer be able to search your image library and will in effect have to recache (or reindex) all the folders. Back to square one as it were.