2 Further Ideas
One:-
When these "some need up to 3 times as long as before, especially
jobs that backup a huge number of small files."
are running, check the memory usage on the W2008 R2 server.
(Windows Task Manager, Performance tab).
Consider adding more memory.
Two:-
There is a setting that can help W2008 R2 DP CMs (ver 7.0 or less) performance.
In the rdmserver.ini file "[Engine]" section add,
WindowsFileRandomAccessFlag=no
Stop/Start DP.
Use DP for a few days and see if performance has been improved.
(In case performance is not improved, remove
WindowsFileRandomAccessFlag=no
from the rdmserver.ini)
By default rdmserver.ini lives in \ProgramData\OmniBack\db40\datafiles\catalog
when DP 7.0 or 6.x runs on W2008 R2.
In case that does not help, some questions...
- Any difference between the OS of the clients, or OS of the Media Agents,
between the jobs that are OK, or faster, and the ones that are now slow ?
- Is the CM now Virtual or Physical ?
- Any DP MAs that were physical, now virtual ?