Bad Performance Caused By Cache Flush: Users report Instance Slowness OverallIssue Many users report the instance is slow doing anything like querying something or switching from one module to another. This behavior happened all of the sudden. It lasted for a while, and then the performance went back to normal. ReleaseLondon Patch 10CauseThe cache was flushed. There are several things that will cause a cache flush. In this specific case, the admin changed a custom system property which had the flag Ignore cache= false. Since the flag was set to false, then at the time the system property was updated, that caused a cache flush. The cash flush caused slowness in all the instance for a while until the cache was rebuilt. NOTE: There are several ways to determine if there was a cache flush. This is just one of them: Navigate to Self-Service > Homepage and select "ServiceNow Performance" from the list2. Change Timespan to 1 day3. In Diagnostics Events click on "Show on graphs"4. If there was a cache flush, the information will be displayed hereResolutionTo prevent the cache flush in the future for the same system property, you can activate the Ignore cache. 1. Go to System Properties module https://INSTANCENAME.service-now.com/sys_properties_list.do 2. Query the custom system property and open it 3. Check the Ignore cache checkbox (when this checkbox is active, even if the system property is updated, the cache will not be flushed) 4. Save the change Related LinksSee KB1000746 - When to use 'ignore cache' on 'sys_properties records for more details on the behavior of the 'ignore cache' field.