The traffic in Coachella is already expected, but you can always make some changes to your routes and your schedule so that you can avoid the traffic the best way possible. It can be expected that the traffic in Indio is going to last for about three weeks because Coachella is happening on a double weekend. Bumper to bumper traffic will already be expected.
The best way to avoid traffic is not to travel Eastbound on Friday as this can cause some problems. Coming back on Sunday or Monday after the weekend will still be traffic. If you have the option to stay longer in the area, you can go back on Tuesday because the traffic will be considerably fewer on that day.
When it comes to traffic at Coachella, one should be prepared for a lot of it and should plan ahead several hours when it comes to getting ideal seats and being able to have ideal camping areas and sites when it comes to setting up in the Camping Area.
The freeway and main roads leading to the site is not too bad for California but once you get in and around the venue you will be facing very bad traffic and it is certainly very hard to get around. Again, this is the reason that one should always plan ahead and make sure that they know where they are going and where everything is taking place.
So yes the traffic is bad at Coachella especially in and around the venue area. The closer you get to the venue the worst the traffic is going to be. Always make sure to plan and plan effectively ahead of time.