Phusion Passenger author here. I'd like to say: if anybody is still on Passenger 3, you should upgrade to Passenger 4. Passenger 3 is very old, over 2 years now. Passenger 4 has received tons of improvements, as documented at "Recent Technical Advances in Phusion Passenger": https://vimeo.com/85970704

Honestly, I'm surprised anybody still talks about Passenger 3 nowadays. The improvements in 4 are so huge that 3 shouldn't even be worth looking at.

Also, the tests don't seem to say how the servers are configured. Passenger's out-of-the-box configuration is designed to conserve resources, not performance, because a lot of our users are on low-memory VPSes. It needs a few minor tweaks to optimize for performance like Unicorn is. With settings like these, it behaves almost exactly like Unicorn:

    # 'x' is whatever your Unicorn worker count should be
    passenger_max_pool_size x;
    passenger_min_instances x;
    passenger_pre_start_url http://yourapp.com/