https://getfelix.dev/topics/performance/ Felix blog posts about performance. en https://getfelix.dev/blog/even-overall-lopsided.html https://getfelix.dev/blog/even-overall-lopsided.html Fri, 23 Oct 2026 00:00:00 +0000 Felix placement kept every broker's leader count near the cluster-wide share, and a single stream could still land 1/1/10 with all its writes on one broker; this is how placement now spreads each stream's leaders too. https://getfelix.dev/blog/fast-without-losing-messages.html https://getfelix.dev/blog/fast-without-losing-messages.html Fri, 23 Oct 2026 00:00:00 +0000 How Felix answers a fsynced publish in a third of a millisecond, writes at the disk's full rate under load, and slows publishers down instead of dropping their messages. https://getfelix.dev/blog/catching-a-one-percent-regression.html https://getfelix.dev/blog/catching-a-one-percent-regression.html Sat, 17 Oct 2026 00:00:00 +0000 Felix's rule is that a release must not be measurably slower than the one before it; this is how same-runner A/B runs, a Welch's t-test and throwaway bisect PRs in GitHub Actions find a 1-2% loss, and why a single benchmark run can't. https://getfelix.dev/blog/one-slow-subscriber.html https://getfelix.dev/blog/one-slow-subscriber.html Fri, 16 Oct 2026 00:00:00 +0000 How Felix keeps one slow subscriber from holding up publishers or other readers, and how a 2% single-publisher loss came from where the feeder gave back a subscriber's byte budget. https://getfelix.dev/blog/ten-parcels-one-envelope.html https://getfelix.dev/blog/ten-parcels-one-envelope.html Sun, 27 Sep 2026 00:00:00 +0000 Raising Felix's QUIC MTU on Linux stalled delivery for good, because UDP GSO turns ten packets into one datagram the kernel refuses and quinn never falls back; this is how we found it, why the cap is 6,550, and why 4,096 is the default.