Loading NSURLRequest in a UIWebView - heap keeps growing

I've got a simple UIWebView loading an NSURLRequest every tim开发者_JAVA百科e a button is clicked. Using Instruments and analyzing heapshots, I'm noticing that my heap is continuously growing. However, none of the objects seem to be my own, as they are all < non-object > WebCore glyph stuff. I'm seeing an increase of roughly 40kB heap growth each time the UIWebView is allocated/deallocated, even after 10+ heap shots.

Why do these objects still exist in memory, and what can I do about it?

I did not manage to not make the heap stop from growing for each successive -loadRequest:. However, I did notice a drastic decrease in live bytes later on, suggesting that the allocated bytes are cleared out eventually.