Chrome Version: 
OS: cros platform:10452.85.0

What steps will reproduce the problem?
(1) download a test image tarball from goldeneye
(2) double click on it to unzip via Wicked Good Unarchiver
(3) launch chromeos recovery utility to burn chromiumos_test_image.bin to USB stick

What is the expected result?
task completes in reasonable time.

What happens instead?
- Unarchiver takes several minutes to unzip.  While this might be acceptable if you clear the notification there's no means to determine its still succeeding.  Need to benchmark against just running 'tar xf' from dev mode machine to confirm there's no additional overhead
- Once archive is mounted the 'recovery utility' claims there's something wrong w/ the image. 'unknown error: IMAGE_INVALID. Please try again'
- If I instead copy the image outside of the archive mount it does work but the copy performance is slow (guesstimate ~1G / minute) to /home/chronos/user/Downloads and equally slow to the usb stick.

Whole task probably takes ~20min and the teemo device is noticeably lagging during the process.