Being faster (in throughput) than Redis doesn't seem that difficult, Redis is mostly single core. But with that restriction comes the magical constraint that you can run Lua on that single core without having to think about race conditions or concurrency. For many complicated systems this is an incredible property and can provide incredible power. Yes, you may eventually outgrow Redis, but if you do then you are entering pretty crazy territory where you will likely need something custom anyways.

All that to say, that particular comparison feels a bit Apples and Oranges to me.