OK, looked it up on dead trees from my library: Ride the Big Red Cars by Spencer Crump (1962, Trans-Anglo Books).

Santa Monica Air Line: 16.85 miles from LA to Santa Monica; 19.20 to end of line at Ocean Park. Running time in 1911, 40 minutes; no later running times given. Frequency: 1 RT daily (1911); every 60 minutes (1913); back to 1 RT daily beyond Culver Junction (1920). Passenger service ended in 1953.

So 46 minutes on Metro Expo line is actually about 6 minutes slower than in 1911, but actually even a bit slower than that because the LA PE station was farther into downtown than 7th/Metrocenter, had street running (rather than a short subway and partial prw in the streets) to get out of downtown, and ran a bit farther into Santa Monica (to Ocean Park) than the current end of the line. Frequency of service, though should be altogether better than it was at any time when PE was running it.

Apparently most Santa Monica traffic ran via Sawtelle: via Venice Short Line, San Vicente Bl., Burton Way, & Santa Monica Bl. It had 30 min. headways in 1911 and still had 40 min. headways in 1934. Running time in 1911 was 52 min. to Santa Monica and 60 min. to Ocean Park. By 1934 it was 60 min. to Santa Monica. Passenger service ended in 1950.

The Expo line decisively beats the Sawtelle line for running time. And again the service frequency for light rail is much greater than anything PE produced. The Hollywood-Beverly Hills-Santa Monica corridor of the Sawtelle line (and others via Hollywood itself) should be covered, eventually, by the subway extension along Wilshire.