What problem does it solve? Web applications slow down gradually as each pull request adds small delays and bundle bloat, and nobody notices until load times become unacceptable. This Skill measures page performance, captures baselines, and compares metrics across branches so regressions are caught before they ship. ## Core Features & Use Cases - Baseline Capture and Comparison: Record TTFB, FCP, LCP, DOM timings, transfer sizes, and bundle sizes per page, then diff current metrics against the stored baseline with regression thresholds. - Resource and Bundle Analysis: Identify the slowest resources, largest JavaScript and CSS bundles, and total network transfer using the browse daemon's perf command and JavaScript evaluation. - Diff-Aware and Trend Modes: Benchmark only pages affected by the current branch with --diff, or review historical performance trends with --trend. - Use Case: Before merging a PR, run a benchmark against your staging URL to discover that LCP doubled and the JS bundle grew 60%, then investigate the offending dependency before users feel the slowdown. ## Quick Start Ask the assistant to run a performance benchmark on your staging URL with baseline comparison, for example by requesting a benchmark of https://staging.example.com against the saved baseline.
