https://rjrowland.com/tags/performance/Recent content in Performance on rjrowlandHugoen-usMon, 27 Jul 2026 09:00:00 -0500https://rjrowland.com/posts/engineering-practices-performance/Mon, 27 Jul 2026 09:00:00 -0500https://rjrowland.com/posts/engineering-practices-performance/<h2 id="measure-first-know-your-bottlenecks">Measure first, know your bottlenecks</h2> <p>Performance intuition is wrong more often than it&rsquo;s right. The thing you&rsquo;re certain is the bottleneck almost never turns out to be. Profile first and let the data decide where effort goes. There&rsquo;s no reliable shortcut around this.</p> <p>Most web application code spends its time waiting, not computing. A request handler calls the database, waits, calls another service, waits, maybe hits a cache, waits again — and the CPU sits idle through nearly all of it. That&rsquo;s why the common bottleneck categories skew so heavily toward I/O, roughly in this order of frequency:</p>