title: CFNetwork memory spike when fetching image
body: <p>I'm profiling my app in Instruments, and have found a troubling amount of allocations by CFNetwork when I use AFNetworking to fetch a remote image.</p>
  
  <p>In one instance I saw 89 MB of allocations (the image is only around 200 KB in size). I've attached a screenshot to demonstrate. Has anyone else noticed this before? The memory is released appropriately but I can't understand why this happens in the first place.</p>
  
  <p><img src="https://i.stack.imgur.com/dVFtV.png" alt="Profile"></p>
  
  <p>Thanks in advance.</p>