[otrs] Shrink database

I have a problem with OTRS (old version, 1.3.2). The database has grown a lot and now it takes A LONG time to load the pages!! How can I shrink or purge the database so that it becomes faster? Just deleting the articles is - IMHO - not the right way, because the articles still remain in the database. Right?! Please help on this. I need OTRS for work and I cannot work in this way, it takes 5 minutes to load the first page and sometimes several minutes to change from one page to the other. It's not my server, because other MySQL programs just work fine! Thanks, marc