Performance boost:

When "idle" isn't idle: how a Linux kernel optimization became a QUIC bug

Cloudflare·Cloud·PerformanceImprovement·5/12/2026

We 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.

Why it matters → Cloudflare shipped measurable performance improvements. Upgrading may reduce latency or infrastructure costs.

Who should care → Engineers running this tool at scale.

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  "link": "https://blog.cloudflare.com/quic-death-spiral-fix/",
  "title": "When \"idle\" isn't idle: how a Linux kernel optimization became a QUIC bug",
  "pubDate": "Tue, 12 May 2026 13:00:00 GMT",
  "category": [
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    "Antonio Vicente"
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