What does "Prefetch views unpack data" in APDQC module do? There is an option in the APDQC (Asynchronous Prefetch Database Query Cache)  https://www.drupal.org/project/apdqc module for:

Prefetch views unpack data

It's unclear what this does. Should this be turned on or left off as default?
Really depends on your workload. In some cases having all of the views data prefetched is faster, in other cases it's slower. If you have 50+ views then it's best to leave it off, if you have just a couple views, turning it on is faster. 

Side note: I created the patch for creating this cache in views, now I wish it was prefixed by the view name so prefetch would be easier.