We really wanted to like Render, but the performance just wasn't there for us when doing a bunch of load testing against Heroku, which is a shame. Hoping they can make it better in the coming months/years cos we really liked the product.
Our tests for simple JavaScript endpoints with a MongoDB call to be just as fast or faster on Render. Additionally the availability of far more tiers of cpu/ram meant we could see the same performance for half the cost.