Fatal error: Maximum execution time exceeded in wp-search-mu Search

My BuddyPress site uses BP Daily Theme, and has been running without problems for 6 months.

All of a sudden yesterday, the site started throwing time out errors whenever users try to post in the Admin system, of the folowing nature:

Fatal error: Maximum execution time of 30 seconds exceeded in /home/pookapro/public_html/MYURL/wp-content/mu-plugins/wp-search-mu/Zend/Search/Lucene/Storage/File/Filesystem.php on line 182

The error seems to occur in a number of different files, on different lines, but always related to the Zend Framework wp-search-mu functions.

My site now has 2,000+ posts, so I wondered if this may be to do with the amount of content in the database?

Any pointers on potential fixes gladly received!