Browser performance work begins with a trace tied to a user action. This track connects field timing collection, interaction latency, retained memory, and rendering cost. Each lesson asks what was measured, what the browser was doing, and what changed after a fix; the goal is a repeatable decision rather than an isolated score.
Topics in this track
- Field Performance Observation and Sample Contracts — Collect browser timing entries with explicit support, sampling, privacy, and interpretation rules.
- Interaction Latency Traces and Main-Thread Contention — Break a slow interaction into queueing, handler, and presentation time before changing code.
- Retained DOM Memory and Lifecycle Investigation — Find roots retaining removed views and verify that cleanup survives repeated route cycles.
- Layout, Paint Regressions, and Containment Decisions — Measure render work caused by DOM changes before applying containment or batching reads and writes.
Prerequisite paths
Browser Execution and Resource Lifecycle; Production Signals and Incident Decisions; Quality and Capacity Engineering.
Practice and check
Build Project: permit browser regression investigation and review Web Development: browser performance diagnosis quiz.
Further connections
React Urgent Input and Transition Work.