PHP 5.1 memory leak?

Hi All, My apologies if this question was already answered, I just couldn't find it on the mail archive. I have a really complex report which uses a tree-like structure of data base objects. Usually it consumes a lot of memory but that it is not really an issue because it is an intranet application with few users and a dedicated server for it. The problem is that the memory allocated by the script is never free'd! My production server uses ubuntu 6.10 PHP 5.1.2 on apache2 using mod_php. When the script is executed, it consumes about 5% of my memory, event when it finishes, I can use 'top' and see that the memory is still allocated: USER NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND www-data 0 110m 98m 4064 S 0 4.9 0:16.51 apache2 If I execute the report several times I can consume as much memory as the number of apache process I have. The funny thing is that on my laptop I use ubuntu 7.04 PHP 5.2.1 an apache2 using mod_php, and the memory is normally free'd when the script finishes, no matter how many times I execute it. Is it a PHP5.1 bug? Garbage collector couldn't handle my complex structure? The only solution is to upgrade to PHP 5.2? Any help would be greatly appreciated. Egon