10 mph on the 10 or 210 mph on the 210.
Now that the 210 runs all the way to Redlands, it's almost as slow as the I-10, with so many using it as an alternative. It does ease up a bit going eastbound, however, once you get past Pomona.
I know. Was there recently to visit the in-laws and sad to see that it crawls almost as much as the 10, at least west of the junction with the Santa Ana freeway (57?).