canvas-performance-optimization

canvas-performance-optimization is a skill for Claude Code, Codex from 0xheycat/isometric-game-skills. It costs 29 tokens per session (396 once invoked), scanned A, original, MIT.

A skill for improving the performance of isometric games drawn on an HTML Canvas. It focuses on finding slow frames, drawing only visible content, grouping image work, caching unchanged layers, and avoiding temporary objects each frame.

In plain words
What is it for?
Use it to profile frame time, hide off-screen tiles, batch tiles from an image atlas, cache static ground layers, reduce allocations, and measure the result again.
Why use it?
It addresses frame drops, stuttering, large maps that lag while moving, garbage-collection pauses, and excessive drawing work. The stated target is a steady 60 frames per second.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to profile frame time, hide off-screen tiles, batch tiles from an image atlas, cache static ground layers, reduce allocations, and measure the result again.

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Install with agentmods
npx agentmods add skills/0xheycat/isometric-game-skills/canvas-performance-optimization
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add 0xheycat/isometric-game-skills --skill canvas-performance-optimization
Clone the repo
git clone --depth 1 https://github.com/0xheycat/isometric-game-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for canvas-performance-optimization

README.md
[![agentmods](https://agentmods.dev/badge/skills/0xheycat/isometric-game-skills/canvas-performance-optimization/github.svg)](https://agentmods.dev/skills/0xheycat/isometric-game-skills/canvas-performance-optimization)
Your own site
<a href="https://agentmods.dev/skills/0xheycat/isometric-game-skills/canvas-performance-optimization"><img src="https://agentmods.dev/badge/skills/0xheycat/isometric-game-skills/canvas-performance-optimization/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for canvas-performance-optimization

Your own site · 80×15
<a href="https://agentmods.dev/skills/0xheycat/isometric-game-skills/canvas-performance-optimization"><img src="https://agentmods.dev/badge/skills/0xheycat/isometric-game-skills/canvas-performance-optimization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 396 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00029 $0.00396
Opus 5 $0.00015 $0.00198
Sonnet 5 $0.00006 $0.00079
Haiku 4.5 $0.00003 $0.00040

Measured 10d ago against content hash c0aa64fa383d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

canvas-performance-optimization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/canvas-performance-optimization/SKILL.md · 53 lines

What it actually says

Canvas Performance Optimization

Overview

Isometric games die by a thousand draw calls. This skill profiles the frame, culls off-screen tiles, batches from the atlas, and removes per-frame allocations to hit a stable 60fps.

When to Use

  • Frame rate drops or stutters.
  • Large maps lag when panning.
  • You suspect GC pauses or overdraw.

Process

  1. Profile first - measure where the frame time actually goes.
  2. Cull: only draw tiles/objects inside the viewport.
  3. Batch draws from one atlas to minimize texture binds.
  4. Cache static layers (ground) to an offscreen canvas; redraw only when it changes.
  5. Eliminate per-frame allocations (reuse arrays/objects).
  6. Avoid sub-pixel blits; snap to integer pixels.
  7. Re-profile to confirm the fix, do not assume.
Profile -> Cull -> Batch -> Cache static layer -> Kill allocations -> Re-profile

Rationalizations (Stop Lying to Yourself)

Excuse Reality
"I know what is slow without profiling" Guessing wastes hours on the wrong thing. Profile first.
"Redrawing the ground every frame is fine" Static ground should be cached. Redraw only on change.

Red Flags - STOP if you catch yourself:

  • Optimizing before profiling.
  • Redrawing static layers every frame.
  • Allocating inside the render loop.

Verification

You are NOT done until every box is checked:

  • Frame time was profiled before and after.
  • Off-screen content is culled and static layers cached.
  • No allocations occur inside the render loop; 60fps holds.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 53 lines · 29 tokens per session scan A c0aa64fa383d

Subscribe to this mod's changes

canvas-performance-optimization is a skill published in the GitHub repository 0xheycat/isometric-game-skills (15 stars, last pushed 28d ago), licensed MIT. It adds 29 tokens to every session and 396 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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