>As a test we have upgraded a machine with SQL server 2008R2 to Windows 10 this morning.
>
>Prior to the upgrade SQL server performed fine. However after the upgrade especially table scan operations where one or two orders of magnitude slower.
>
>Any idea, what could be at play here? The specs of the machine are just fine intel I5, 3.1Ghz and 8 Gb of RAM. The task manager does not reveal anything stressing resources.
>
>Walter,

SQL Server 2008 and SQL Server 2008 R2 are not supported by Windows 10. Check

https://social.technet.microsoft.com/Forums/en-US/bb5f2199-f283-4249-a029-53978d637148/sql-service-stops-working-after-windows-10-upgrade?forum=sqldatabaseengine

and the article referenced in that thread https://support.microsoft.com/en-us/kb/2681562