According to the compatibility reporter and https://arewee10syet.com/, this addon is not compatible with e10s (aka Firefox Multiprocess). The add-on is not at all interacting with tab contents, so it seems like it can't be too hard to establish said compatibility. That would be great, because it would mean that once e10s is rolled out for more people, this add-on won't prevent anyone from using it :)
According to the compatibility reporter and https://arewee10syet.com/, this addon is not compatible with e10s (aka Firefox Multiprocess). The add-on is not at all interacting with tab contents, so it seems like it can't be too hard to establish said compatibility. That would be great, because it would mean that once e10s is rolled out for more people, this add-on won't prevent anyone from using it :)