Useful Rated 4 out of 5 stars

Useful but be careful not to use Cookies Manager+ to delete all your cookies - it's extremely slow (100% CPU for several minutes before I gave up) - whereas Firefox's built-in function is instant.

This review is for a previous version of the add-on (1.5.1).  This user has a previous review of this add-on.

Can't reproduce it. Just deleted over 3000 cookies in an instance with maybe 10% cpu usage.
Perhaps you have another addon that interfere?