This is for other random people finding this thread as much as yourself…
optimus-manager is hacky. It requires extra unsupported options be set, such as to SDDM, or to replace GDM entirely with another version, it also automatically deletes mhwd files … and so on.
And thats not even getting to its actual performance.
If you really need (most dont - judging by posts here a not insignificant number of users erroneously believe one of these utilities is required for hybrid graphics to work) a switcher program similar to it I might suggest these as better options: