So we've been having this issue at my company with jobs not running from the job conductor.  We have about 20-30 jobs that run every 5min.  While watching the MySQL admin server, I noticed every time a job runs, it does a lookup on the tasexecutionhistory table.  The problem is that this table is fairly large (~500,000 records) and by default, has no indices. 

Anyways, I added 3 indices to the table on the columns idquartzjob, taskstartdate, and idremotejobexecution (These seem to be the columns most used in the where clauses when Talend runs a job).   This has no solved our issue of jobs not running, and has sped up the job conductor screen as well (Not sure if related, but seems so). 

I hope this info helps someone else.