the problem happens with the combination of prime+vulkan+vsync on 435 drivers. render offload, while a good thing that nvidia is doing something for hybrid graphics on linux is also not very practical because even when your not using the nvidia gpu it has to remain powered on because the xorg process needs to be run on the nvidia for offload to work.
for everyday use you end up using the power cost of 2 gpu's while only getting the benefit of 1 unless you run the program using the launch variable.
i dont have concrete benchmarks but comparing the performance between prime and offload also didnt fare well for render offload.
red faction: remarstered on render offload and no vsync struggled to get 50+ fps while on prime with vsync disabled it easily hits 70+ fps. (identical settings, stock clock/mem)
offload also will not work with coolbits, so no fan or clocking capabilities. aside from the novelty of it being the latest shiny & new thing available, it's really nothing to get excited over and was more disappointing than anything else in it's current state so i'll be sticking to a prime setup and possibly add the functionality of a third mode to optimus-switch for this render offload so i can easily switch back and forth to check the progress on it if any.