I just went through this last week. My car got upgraded to the STAR program, so I don't have to dyno it - they just plug into the OBDII port for a couple of minutes and give the car a cursory look to make sure it isn't too heavily modded. The whole smog test took less than 10 minutes.
The actual pain was getting ready for it: the car had been throwing a code for a year and a half or so, casual googling wasn't helping. When it came down to the wire I had to get serious; it turned out to be the DMTL pump. Got one on Amazon for $50, cleared the code, but then getting the OBDII tests to complete was a PITA. To get the cat test to show ready, I had to drive for about 20 minutes under 3000RPM and under 60MPH.
