This addon has to be the best of its kind because it does it job and just weight a mere 9kb, not like the others. But this addon requires update for it to be compatible with e10s.
After updating to FF 53.0, multiprocess stopped working as well as this addon. After using Addon Compatibility Reporter, it seemed this addon cause FF 53.0's multiprocess not enabled because of incompatibility. Simply disabling this addon made the multiprocess working again.