When "idle" isn't idle: how a Linux kernel optimization became a QUIC bug2026-05-12Congestion ControlDebuggingQUICQUICHENetworkingHTTP3RustWe investigated a bug where CUBIC's congestion window became pinned at its minimum floor, causing a performance to plummet. The fix involved correctly measuring idle periods to distinguish RTT wait times from actual application idleness....Esteban CarisimoAntonio Vicente