Neither this comment nor the article clearly spell this out: when you use the production version of React, much of the developer-assisting error checking is removed (not just propTypes[1], but many other error checks[2]), so you don&#x27;t need to worry about the end-user performance impact of propTypes.<p>As an example of how much this helps, one React-heavy page of mine dropped from 1500ms to 300ms by switching versions, according to my browser profiler.<p>[1] <a href="https:&#x2F;&#x2F;facebook.github.io&#x2F;react&#x2F;docs&#x2F;reusable-components.html#prop-validation" rel="nofollow">https:&#x2F;&#x2F;facebook.github.io&#x2F;react&#x2F;docs&#x2F;reusable-components.ht...</a><p>[2] <a href="https:&#x2F;&#x2F;facebook.github.io&#x2F;react&#x2F;downloads.html#development-vs.-production-builds" rel="nofollow">https:&#x2F;&#x2F;facebook.github.io&#x2F;react&#x2F;downloads.html#development-...</a>