I had exactly the same experience. Love the optics on the 20/1.7 but the AF is notoriously slow. The Oly 25/1.8, in contrast, is blazing fast on the E-P5. Interestingly, so is the Pany 14/2.5.
Here's one from earlier today, E-P5 and 25/1.8, at f.2.8:
Birthday Girl by
bingley0522, on Flickr