Code review comment for lp://staging/~verzegnassi-stefano/ubuntu-docviewer-app/workaround-fix-1432412

Tested on bq device and works fine. We may need to re-visit on meizu device (which runs vivid, and a newer kernel) because it seems to never spin more than 1 core even under heavy load in this app.

For now, I say approve as bq device is only one shipping, and we can analyse meizu/vivid issue separately.