A recent update (LP: #1778011) in 18.04 has restored the PRIME switching mechanism in Gdm 3 only, while still leaving out support for other login managers (such as Lightdm, and SDDM).
In addition to this, we should restore the default pci power control profile for the dGPU when re-enabling performance mode, as we do in Ubuntu 18.10.
A recent update (LP: #1778011) in 18.04 has restored the PRIME switching mechanism in Gdm 3 only, while still leaving out support for other login managers (such as Lightdm, and SDDM).
In addition to this, we should restore the default pci power control profile for the dGPU when re-enabling performance mode, as we do in Ubuntu 18.10.