While it seems to not pose a problem on the simulator, using performSelectorInBackground on the device causes memory leaks. Or at least that's what Instruments indicates. Looking at the code I don't have a single clue what the cause could be. I tried to strip the affected code to a bare minimum but still strangely Instruments keeps showing a leak every time this piece of code is executed.

Anything unusual going on here?

 //In viewcontrollerA:
    -(void)mainLoop
    {
        [self.viewControllerB performSelectorInBackground:@selector(calculateTotals) withObject:nil];

            //This gives the same problem
            //[NSThread detachNewThreadSelector:@selector(calculateTotals) toTarget:self.viewControllerB withObject:nil];

            //UI stuff ...

    }

    //viewControllerB:
    -(void)calculateTotals
    {
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

        //Heavy calculations ...


        [pool release];
    }