Use this settings page to configure .NET coverage analysis.
Use preloaded Unit Test runners
If selected, speeds up the startup phase of unit tests coverage analysis. Normally, you should not disable this setting unless asked by the JetBrains Rider support.
Use NGen images if supported
If selected, may speed up coverage analysis: The application under coverage executes faster. Note that in some cases, using NGen images might be not possible. This will result in an application exception in case of getting coverage of an app and inconclusive tests in case of getting coverage of unit tests. In both cases, the setting must be disabled.