XML_HTMLSax - memory leak

Hi, I'm using XML_HTMLSax in script which automatically updates database recors by gaining information from some other web pages. The script should usually parse more than 2000 pages so I got into problems with memory leak, even if I try to unset parser object after parsing one page. Memory is not freed (I checked it by memory_get_usage and amount of alocated memory is growing.) So, I would need advice how to free memory after using XML_HTMLSax object. XML_HTMLSax API doesn't provide any method to do that, maybe I should adjust XML_HTMLSax somehow? Thanks for advice. Lubos