Measure before and after so you can prove it got faster
Performance work without numbers is guessing. Capture the baseline before you optimize, then measure after. The difference is the proof.
'It feels faster' means nothing in a meeting. '2.1 seconds down to 1.4 seconds' means everything. If you're going to spend time making something faster, measure it before and after so you have actual evidence of improvement.
How fast does the page load? How quickly can the user interact with it? How much does the layout shift while loading? These are the numbers that affect both user experience and search engine ranking. Tools like Lighthouse, PageSpeed Insights, and Vercel Speed Insights give you these numbers for free.
Before making any performance change, run a speed test and save the results. Make your changes. Run the same test again. Compare. If the numbers improved, ship it. If they didn't, your 'optimization' didn't actually optimize anything.
Before and after any change motivated by speed. Also useful when adding new features. If you're adding something that makes the page slower, benchmarking tells you exactly how much it costs.
Product leader shipping across enterprise SaaS, AI in production, and 0→1. Writing about what actually ships — not what sounds good in a deck.