The talks are scheduled for 30 minute sessions, but the speakers have to save five minutes at the end for room changing. If you throw in Q&A, then your talk might be just 20 minutes or less. That's like 10 slides (unless you're Stas Bekman, of course).
This isn't necessarily bad. Look at the fun and info that you can get out of lightning talks. Sometimes long talks aren't the best: you can end up with filler.
Whatever... I'm looking forward to the early afternoon talks covering webapps in Python.