SQL Server slow after host reboot
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.