SkillVaultskills Browse all 500 skills

Networking · Version 1.1.0 · Reviewed 2026-08-02

HTTP/3 & QUIC Performance Advisor

Make a defensible decision about handshake latency analysis and packet-loss diagnosis with evidence, explicit trade-offs, and a verification plan.

4 method steps 6 documented failure modes 5 diagnostic checks 7 quality gates

Diagnoses QUIC handshakes, connection migration, head-of-line behavior, packet loss, congestion control, and HTTP/3 deployment regressions.

₹99 one-time

Get this skill archive

What this skill helps you do

  • Handshake latency analysis
  • Packet-loss diagnosis
  • HTTP/2 versus HTTP/3 comparison

How HTTP/3 & QUIC Performance Advisor works

You provide

Schema, query plans, and the real access pattern

It inspects

Plan accuracy and lock behavior for handshake latency analysis

It decides

A packet-loss diagnosis change weighed against write cost

You verify

Re-measured plan with buffer reads and timing compared

What it checks first

HTTP/3 & QUIC Performance Advisor diagnoses QUIC handshakes, connection migration, head-of-line behavior, packet loss, congestion control, and HTTP/3 deployment regressions. Use it when the work involves Handshake latency analysis, Packet-loss diagnosis, HTTP/2 versus HTTP/3 comparison.

  1. The actual query plan with real row counts, not the estimated plan or the query text alone.
  2. Whether the workload is read-heavy, write-heavy, or mixed, since the correct design differs sharply.
  3. Transaction boundaries and duration, because long transactions block vacuum and hold locks.
  4. Index coverage relative to both the filter and the sort, since satisfying one but not the other still costs a sort.
  5. Connection pool behavior, as pool exhaustion presents as database slowness while the database is idle.

Failure modes it recognizes

  • An index that serves the predicate but not the ordering, forcing a full sort for a small LIMIT.
  • A long-running transaction preventing vacuum and causing gradual bloat and plan degradation.
  • Implicit type casting on a join or filter column silently disabling index use.
  • Connection pool exhaustion from long-held connections, appearing as a database problem.
  • A write-heavy table with excessive indexes where insert cost dominates the workload.
  • Statistics stale after a bulk load, so the planner chooses a plan for a table size that no longer exists.

Answers it will reject

  • Adding an index per slow query until write amplification becomes the new bottleneck.
  • Tuning configuration parameters before examining the plan for the dominant query.
  • Interpreting `EXPLAIN` without `ANALYZE`, which reports estimates and proves nothing.
  • Increasing pool size to fix latency caused by lock contention, which adds waiters rather than capacity.

Decision rules it applies

  • Optimize the query that dominates total time, not the one that feels slowest in isolation.
  • Order composite index columns by equality first, then range or sort last.
  • Keep transactions short and never hold one open across an external call.
  • Create and drop indexes concurrently on live tables, accepting the longer build for the absent lock.

Evidence it asks for

  • `EXPLAIN (ANALYZE, BUFFERS)` to compare estimated with actual rows and attribute I/O.
  • Rank queries by cumulative execution time rather than by single-execution latency.
  • Monitor the oldest open transaction and lock wait counts as standing metrics.

The method inside

  1. Map the artifact, actors, boundaries, and invariants relevant to handshake latency analysis.
  2. Trace concrete failure or abuse paths for packet-loss diagnosis; do not report checklist items without a mechanism.
  3. Prioritize HTTP/2 versus HTTP/3 comparison findings by impact, likelihood, confidence, and cost of correction.
  4. Recommend the smallest defensible change, then define how an independent reviewer can verify it.

Deliverables

  • Handshake latency analysis assessment
  • Packet-loss diagnosis decision and action plan
  • HTTP/2 versus HTTP/3 comparison verification checklist

Evidence requirements

  • Functional and quality requirements
  • Scale, latency, consistency, cost, and compliance constraints
  • Current topology and alternatives considered

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

HTTP/3 reduced median latency but made p99 worse for mobile users on lossy networks. Help us identify why.

Expected output

The regression is not HTTP/3 overhead alone: your server resets congestion state after connection migration, so users switching towers repeatedly restart in slow start. Compare migration telemetry and retained path state before changing protocol defaults...

Boundaries and compatibility

Ideal for

  • Handshake latency analysis: produce a decision or artifact grounded in supplied evidence.
  • Packet-loss diagnosis: produce a decision or artifact grounded in supplied evidence.
  • HTTP/2 versus HTTP/3 comparison: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Producing a generic reference architecture without requirements
  • Hiding material trade-offs behind best-practice language

Agent compatibility

  • GitHub Copilot custom agents
  • Claude Agent Skills / SKILL.md
  • Any instruction-following chat model

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.