Objective-C Cocoa-Touch WebView Memory Allocation doesn't stop rising

Related to this question: Memory leak tool tells me zero leaks but memory footprint keeps rising

I also have a rising memory-footprint, but I don't allocate images, and more importantly, I don't do anything in the background. There's just a UIWebView on the screen, showing a JavaScript-free page. Here are two screenshots from the profiling instrument, one is 10 minutes after the other, with zero interaction and zero background activity:

(NOTE: If I set the Allocation Lifespan radio button on the left on another value, it does no difference. The live bytes have rising by about 6MB within 10 minutes.)

Now my question:

Is this an instruments-bug? Or is the WebView alloc开发者_JS百科ating more and more memory? Or do you think it's impossible and that I must have gotten something wrong here?

Aww sorry, there seems to have sneaked in some JavaScript that made the problem. Using a test HTML page, memory remained static.