My impression, it’s only really that bad during “rush hour”, at which time all those freeways turn into long-term parking lots.
During other hours, it’s not all that bad except on the stretch of westbound-I-80 through Berkeley, which is bumper-to-bumper 24/7/365. (well, 24/7/366 this year.) Once you get through that, it should be okay.
Fun fact: I-80 and I-580 merge and later diverge, such that the stretch through Berkeley is both of those freeways at once. But their official designated directions are opposite: So when you’re on westbound I-80 you’re simultaneously on eastbound I-580 and vice-versa. So either way you’re traveling west and east at the same time.