I would think that those driving IN their house (i.e. motorhome) feel things differently than those driving truck and 5th wheel/trailer.
There have been many discussions of I-5 versus 99 on these forums, northbound and southbound. There is never a consensus. Last time I drove 99 northbound, it was absolutely awful. But by now, there may have been road work that improved it. Last time I drove I-5 northbound, it was better than I expected, with what looked like new pavement on many stretches. So there ya go.
CA Traveler...I've taken that same route E/W through Bakersfield many times. I read somewhere on this forum about an alternate to 46 between I-5 and 99. I took it a couple years ago and it was a breeze, much less populated, less traffic. I think it might be 7th Standard Rd. I can't remember. Does anyone here know?