In LR 4, if you call LrLogger (“”) -- with the empty string as the name -- and enable the logger in the plugin's LrInitPlugin, then the logger will enable and capture LR 4's internal logging. This didn't happen with LR 3. Using a unique non-empty name avoids this problem.
With a large catalog, I've observed almost 7,000 log entries per second! I wonder if at least some of the reports of LR 4 being unusable are caused by this bug? The user of my Any Tag plugin who called my attention to the symptoms was experiencing lots of LR 4 slowth, which disappared as soon as he disabled the plugin.
Some example log entries:
12/03/06 06:46:48 LibraryPreloadRootPixels DEBUG requesting preload for image #30: 903294
12/03/06 06:46:48 LibraryPreloadRootPixels TRACE got results for image: 903294
12/03/06 06:48:55 DevelopLocalizedSettingsController DEBUG Attempt to get non existent property: gradient.enabled
12/03/06 06:48:56 DevelopLocalizedSettingsController DEBUG Attempt to get non existent property: gradient.enabled
12/03/06 06:48:59 LibraryView TRACE For state: loupe, image now entering view: loupe
Interestingly, there's a log entry hinting at why reverse geocoding failed intermittently when LR 4 was first released; for some reason, perhaps a misconfiguration, Google was limiting the number of queries:
12/03/06 06:46:47 AgReverseGeocodeService WARN no results in response OVER_QUERY_LIMIT