If you have performance issue please switch to Simplified mode on Common tab of Midnight Lizard's settings popup.
In case you have problems on most websites use 'Set as default' button after changing the mode.
All addons that change at least something on the pages you visit have to require "Access your data for all websites". It does not mean that they actually do something with your data...
Midnight Lizard is an opensource project and does not collect or send your data anywhere.

Best regards
Midnight Lizard