Quartz.NET scheduler suddenly taking a while to return a job detail

I have been using Quartz.NET in my a开发者_运维百科pplication a lot over the past few months, and its performance has always been great. Yesterday, it suddenly began taking much longer than usual to execute something like the following:

JobDetail jobDetail = sched.GetJobDetail(jobName, jobGroup);

Usually the time it takes is not even noticable, and now it takes at least 2-3 seconds - and when adding up multiple of these the speed is appaling.

What can be causing this? If it's any help, I'm using Quartz.NET with an ADO.NET store, and access to this database seems as fast as ever.

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Do you have indexes on the tables? Perhaps the table has now had enough entries that this matters?