In order to make driving in Davis easier for you it will be helpful to know about the local traffic patterns. Or avoid the whole thing by telecommuting. The City of Davis also has a program called Street Smarts that provides information on using transportation in town.
on the UCD campus
Busy times include 9AM and lunchtime. Watch where you're going, and look out for people who aren't paying attention! Pedestrians should be courteous and walk on sidewalks rather than in the bike lanes. If you're forced to walk in a bike lane, please try to keep to the right-most side. Such common courtesy is especially important when there are a lot of folks on the move.
The numerous seemingly untimed stoplights on 5th Street, which turns into Russell Boulevard on the West side of town, contributes to what is probably the worst street traffic in Davis during commute hours. If you're trying to get across town during 8AM-9PM and/or 5PM-6PM, you might be better off using Covell Boulevard or Interstate 80 instead.
The most predictable traffic jams in the Davis area on I-80:
7AM-9AM Eastbound (folks going to work in Sacramento)
Fridays 3PM-7PM Eastbound (folks going to Tahoe, etc. for the weekend)
This short stretch of highway rarely sees any traffic jams, except when there's a wreck.