render-bench

name	render-bench
description	Run RaTeX rendering performance benchmarks (100-formula PNG/SVG/PDF, cold-vs-hot font cache timing, phase breakdown). Use when profiling render performance or comparing before/after optimization changes.

Render performance benchmarks

Cross-tool layout (Cursor / Claude Code / Codex)

• Canonical copy: repository root skills/render-bench/SKILL.md (this file).
• Tool entry points (symlinks to this file in-repo):
  • Cursor: .cursor/skills/render-bench/SKILL.md
  • Claude Code: .claude/skills/render-bench/SKILL.md
  • Codex: .agents/skills/render-bench/SKILL.md

When to use

• After changes to rendering paths (especially renderer.rs, fonts.rs, standalone.rs, outline caching, font loading).
• Before committing optimizations — run cold first so cache impact is visible.
• Comparing before/after for a specific renderer (PNG vs SVG vs PDF).

Prerequisites

• Rust toolchain with --release.
• KaTeX TTFs in fonts/ (committed in-repo; 20 .ttf files).
• (Optional) CJK/emoji system fonts for the full CJK/emoji categories.

Commands

1. Full 100-formula benchmark

cargo test -p ratex-render --test bench_render --release -- --ignored --nocapture

Renders 100 formulas across 6 categories (math, complex, matrix, cjk, emoji, chem) in PNG, SVG, SVG-standalone, and PDF. Prints per-category averages and overall throughput (formulas/sec).

Warmup: 1 iteration per formula. Measurement: 3 iterations, averaged.

2. Font cache cold vs hot timing

cargo test -p ratex-render --test font_cache_timing -- --ignored --nocapture

Measures 3 formulas: first pass (cold — disk I/O for font loading), second pass (hot — OnceLock cache hits). Reports speedup ratio.

3. Render phase breakdown

cargo test -p ratex-render --test phase_breakdown --release -- --ignored --nocapture

Per-formula breakdown: parse+layout vs render phase timing. 6 formulas including CJK and emoji cases. Warmup: 3 iterations, Measurement: 10 iterations, averaged.

4. Compare before/after (quick diff)

Useful when optimizing a specific path:

# Before (on main)
cargo test -p ratex-render --test phase_breakdown --release -- --ignored --nocapture 2>&1 | tee /tmp/before.txt

# After (on branch)
cargo test -p ratex-render --test phase_breakdown --release -- --ignored --nocapture 2>&1 | tee /tmp/after.txt

# Diff the tables
diff /tmp/before.txt /tmp/after.txt

Quick checklist

1. Run cargo test -p ratex-render --test bench_render --release -- --ignored --nocapture for the full picture.
2. For quick iteration, use phase_breakdown (faster, 6 formulas).
3. For font-loading specific changes, use font_cache_timing.
4. Always use --release — debug builds are 10-50× slower and meaningless for perf comparison.