When servicing SCCM (for example from 1802 to 1806) the compatibility level was changed from 110 to 130. The compatibility level was set to 110 specific because of major performance issues with level 130.
With the compatibility level being reset the update from 1802 to 1806 is already running for 43 hours and still not completed (CE level is already changed back to 110). Why not running a few SQL query's, based on this article: https://support.microsoft.com/en-us/help/3196320/sql-query-times-out-or-console-slow-on-certain-configuration-manager-d to check performance for each possible level. Then based on the results, change the compatibility level? If we have this kind of performance issue and duration each time we service SCCM, it will not be a joy.