If checked then, when checking for changes etc, the plugin will ignore the possibility that there have been changes in the parent stream that affect the contents of the stream being polled.

This is purely a runtime optimisation for when AccuRev is being used as a normal VCS and not taking advantage of its stream inheritance.
When used with reftree or workspaces this will be used to limit the number of hist commands issued to calculate the changelog. Upstream changes would be considered since we use update to determine actual changes.