I've inherited an EE site that has a tag cache problem. The tag cache is grows rapidly and seems to be accelerating in its rate of growth recently.
The problem this presents is that the tag cache can grow so large at times that when EE needs to clear it, it actually takes so long the whole process times out leaving a white screen (the error is a timeout).
It's so bad that, despite a routine that we run that should clear the cache on weekdays, 3 times per day, over the weekend it can grow to over 5GB in size!
I have an inkling that it's a combination of web spiders (e.g. Google bot) and the weird and wonderful setup that this site has (essentially using some templates as front-controllers for subsections of the site).
I guess somewhere along the line, something is probably creating an endless tree of URLs that are being spidered and this is resulting in the massive cache.
This is just not right and I wondered if anyone else has experienced similar issues with the tag cache and how they overcame it.