Performance impact: medium - even when no FVD tabs are openend.

Hello,

in Firefox v64 there is new TaskManager (shown on about:perfirmance), that shows the load, generated by every tab and addon. In my PC the FVD addon is shown with the poerormance index 1,3 or more - and commented with "Energy impact- Medium", even if there is no tabs with FVD opened.

Not that i see constant CPU load by firefox over 2%, but still it is somehow strange, that the addon, that should not do anything in background (when inactive) still marked as "Impact - medium".

Pls comment on this.