All of these answers are accurate. Mornings are fine, if you leave before 7:35 or after 9:30. Evenings on Sir Francis Drake can be slow, but you can also sneak through Ross via Kent Ave or Laurel Grove. These options are not a whole lot faster, but they can keep you moving.
The bike path is a great commuting path. This runs through the heart of San Anselmo, and heading east can take you directly to the ferry terminal in Larkspur or south across the Golden Gate Bridge.
The more adventorous can head over Mount Tam on bike, horse or foot.