That's weird considering I've heard a lot praise for React in how quickly it makes developers iterate and ship. Granted React is easy to mess up in a larger scale, but most of the time I feel like it's the engineer's faults for not researching the implications of their dependencies and code or knowing how to profile/debug well.

I know that sounds like a copout, but it's just my personal experience. We just rewrote a slow React app some person that didn't know what he was doing did at work and it's fast and fine now.