David Liontooth wrote in gmane.org.wikimedia.mediawiki:
OK, thanks. I've not had problems with Turck on a single wiki within a database shared by several others, but I haven't exactly stress-tested it. As I don't clearly need the extra performance, I'll turn it off in LocalConfig for now.
if you do decide you would like to use in-memory caching, you can replace Turck with memcached (http://www.danga.com/memcached/). the same problem exists with shared databases, but you can simply run several copies of memcached and specify a different one in each LocalSettings.php.
memcached is also quite a bit more tested in general, since it's used on Wikipedia.
Dave
kate.