Why does my job wait so long before being executed? or: Why is my job being overtaken by other jobs in the queue?#
There are several possible reasons for to be queued for a long time and/or to be overtaken …
… later submitted jobs with a higher priority (usually these have used less of their share then your job).
… by jobs with lower priority that are sufficiently small and specified a wall clock limit to allows them to be considered for backfilling