Kivi project is all about winning benchmarks, I don't think that many of its benchmark specific "optimizations" are useful in real projects. It doesn't have really important feature for building reusable components, it is impossible to return Components as a root node for another component (HOCs that just wrap another components). This tradeoff was made to implement efficient event delegation because we need to map 1-1 DOM Nodes with Component instances. Its API is quite ugly, all API decisions were made to squeeze out the latest bits of performance, right now profiler reports are mostly dominated by "native" code. This project was an inspiration for many other libraries, if you want to learn how to build a really fast web UI library, take a look at its source code. Code base are quite ugly, but most of the time it was made this way to win benchmarks.