An explanation of how they achieve the higher performance: https://million.dev/blog/virtual-dom
And how they implement it: https://million.dev/blog/behind-the-block
And how they implement it: https://million.dev/blog/behind-the-block
Personally, I feel like we are getting to the point of over-optimization on the front-end. Is a 70% optimization in performance, which may lead to a, say, 5% increase in user experience, worth the increased complexity/maintenance cost of another library integration? I think for most companies that are not Amazon or Google - probably not.