SQL Server slow after host reboot I work with SQL Server 2008R2 and the server is rebooted in a monthly basis due to Windows patching. Usually the reboot takes place in the last Sunday of each month during the morning period. However every time that happens, some critical jobs that are executed in a daily basis late at night become incredible slow taking more than the double of the time to complete. After a few days, they get back to their usual duration.
I understand that the caches are cleared and some queries will recompile but would that make queries to take the double of the time (from usual 4 to 8 or more hours) ?
And why they get back to the normal behavior without no intervention at all after a few days?
I wonder what could be done to minimize (if not completely avoid) the impact of this monthly reboots.
Thoughts?
Reason for slowness is that - your buffer pool (including other caches e.g. plan cache, etc) are nuked when sql server is restarted.

Couple of things that you can do -


After reboot, if you know what tables are getting hit by your critical jobs, just cache them (doing select * ) into the buffer pool.
Check to see if your server is configured properly  - e.g. power setting (high perf mode) , max memory setting, etc. You can use sp_Blitz and follow general best practices.


I am assuming that you are regularly updating stats and / or reorg/rebuilding indexes as and when required.