tl_search_index goes extreme

Hi there,

We have a question regarding the maintainence of a website http://www.soerenk.dk. The tl_search_index has extremely many entries, just a 4 clicks an the backend and numbers goes from 0 to 1700 and this continues — a few days and the numbers is about 50.000. The backend is very slow and the database is huge unless we clear everything in tha maintainence regularly. Is there something wrong here or is this normal?

And can someone tell us what information the tl_search_index holds?

Many thanks!