SQL Server is running slow after a certain amount of time We've been experiencing some issues with our SQL server recently.  I have noticed that some of our SQL jobs are running longer than normal.  One job normally runs in under 3 minutes will take over a day.  A job that runs in about 15 seconds will take over 2 minutes.  These jobs calls a simple stored procedure.

I have looked at the CPU usage and memory and everything looks fine.  I am not sure what else I can look at.  It seems odd that everything will run fine for a bit but then after a week or so, the jobs start taking long to run again.  The only thing I could do it make it better again is to restart the SQL service.

We are running SQL Server 2012 SP2 Enterprise Edition on Windows 2012 R2.  We are using AAG on this particular server as well.

Anyone have any ideas what to look at to see why the performance tanks after a few days?  I had some performance counters captured but I didn't see anything jump out.  I don't see any memory errors either.
I'm not sure how this recommendation will be viewed, but based on the vague nature of your problem description and report of steps you've taken, I'd recommend going with something that attempts to answer some of the 'what do I look for / at?' for you like the stored procedures Sp_blitz and sp_askbrent over at brentozar.com.  You may need to start with some basic health checks before you dig into the causes of for your performance issues on particular jobs. While this doesn't specifically answer your question, it's somewhere you can start. Brent's work is awesome and you'll find actionable output  that you will point you to potential solutions. Otherwise start with using activity monitor to see what else may be hitting the same tables while your jobs are running. At the same time check your growth patterns and see if you've had some growth recently within the tables your hitting. You may be limited in what you can retrieve depending on whether or not you're warehousing DMVs (or restarting the services for that matter) so setting of the built-in warehouse to store growth (etc) might be something you need to look into. In general if you have a solution in place to retrieve and retain DMVs you'll be able to act when problems like this come up. Sorry if I'm all over the place with this response.