In my experience Safari 3 leaks less than Safari 2. And it leaks less on Leopard than it did on Tiger. With Safari 2 on Tiger I had to restart Safari at least once a day, or it would be using well over a gigabyte of real memory.

I think the Flash plugin leaks memory significantly, though.

I'm betting it's NSURL resourceDataUsingCache: NO, which has a low-level memory leak.

From what I've read and tested it could also be sheets that leak. I just posted so people know to check and perhaps re-launch Safari from time to time given the long uptimes many Macs see.

Test code, compile and let run, watch process mem usage gradually increase:

Compile and run the following example code:

int main (int argc, const char * argv[]) {
	while( 1)
	{
		NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
		NSString *prefsBBURL = @"http://planetx.geneseo.edu/bb/";
		NSData *data;
		NSURL *url;
		// sorry about the pounding
		url = [NSURL URLWithString: prefsBBURL];
		data = [url resourceDataUsingCache: NO];
		[pool release];
	}
    return 0;
}