If you’re struggling with depression, know that you are not your thoughts. Depression warps reality so thoroughly that you cannot see what’s real as hard as you try. There is hope. Life is worth it. You will get through this.
React is typically fast enough.
But here's a simple way to optimize performance: Decompose components so state changes impact a small amount of JSX.
Example:
If a complex page has a form, put the form in a separate component. Now form state changes only re-render the form.