Performance issue

The px:mediaoverlay-rearrange test in mediaoverlay-utils takes a lot of time, so much that Travis thinks the build has stalled (Travis stops after not having received any output for 10 minutes). Debug messages show that it's the XProcSpec part that takes so long. More specifically the "grouping x:expect elements with their x:context..." and "reporting..." seem to take the most time.

Start with the px:mediaoverlay-rearrange test in mediaoverlay-utils and use its debug messages to examine the XProcSpec stages for grouping x:expect elements with their x:context and reporting. Done means the test no longer appears stalled to Travis or exceeds its 10-minute no-output limit.

Written by the indexing model from the issue text.