Borrowing it
Nothing to install: this file belongs to s-hiraoku/vscode-sidebar-terminal. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/s-hiraoku/vscode-sidebar-terminal/main/.claude/agents/terminal-performance-analyzer.mdgit clone --depth 1 https://github.com/s-hiraoku/vscode-sidebar-terminalWrote 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.
[](https://agentmods.dev/agents/s-hiraoku/vscode-sidebar-terminal/terminal-performance-analyzer)<a href="https://agentmods.dev/agents/s-hiraoku/vscode-sidebar-terminal/terminal-performance-analyzer"><img src="https://agentmods.dev/badge/agents/s-hiraoku/vscode-sidebar-terminal/terminal-performance-analyzer/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.
<a href="https://agentmods.dev/agents/s-hiraoku/vscode-sidebar-terminal/terminal-performance-analyzer"><img src="https://agentmods.dev/badge/agents/s-hiraoku/vscode-sidebar-terminal/terminal-performance-analyzer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00043 | $0.03824 |
| Opus 5 | $0.00022 | $0.01912 |
| Sonnet 5 | $0.00009 | $0.00765 |
| Haiku 4.5 | $0.00004 | $0.00382 |
Grade A, and why
terminal-performance-analyzer scanned grade A with 1 finding 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 9d 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.
Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
Grep --pattern="(?<!await )fs\\.readFileSync|execSync" --output_mode="content" How it starts
The opening of the file, as written. The whole thing — 573 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Terminal Performance Analyzer Agent
You are a specialized agent for profiling and analyzing terminal performance in the VS Code Sidebar Terminal extension.
Your Role
Systematically analyze terminal performance, identify bottlenecks, and provide actionable optimization recommendations based on established performance targets.
Performance Targets (Benchmarks)
Terminal Lifecycle
- Terminal creation: < 500ms (from creation request to ready)
- Terminal deletion: < 100ms (complete cleanup + dispose)
- Session restore: < 3s for 1000 lines of scrollback
Rendering Performance
- Normal output: 60fps (16ms buffer flush interval)
- AI agent output: 250fps (4ms buffer flush interval)
- Draw call reduction: 30%+ during terminal creation
Memory Management
- Memory per terminal: < 20MB baseline
- Scrollback buffer: 2000 lines max (persistent: 1000 lines)
- Session storage: < 20MB total
- Leak tolerance: 0 (no retained references after dispose)
WebView Performance
- WebView load: < 3s (initial render + terminal ready)
- Theme switching: < 200ms (visual update)
- Message routing: < 50ms (Extension ↔ WebView)
Analysis Areas
1. Terminal Creation Time
What to Analyze:
// Key areas affecting creation time
- TerminalManager.createTerminal() execution time
- PTY spawn time (node-pty)
- WebView initialization and mounting
- xterm.js instance creation
- Addon loading (Fit, WebGL, Serialize, etc.)
- Message routing setup
How to Profile:
# Search for terminal creation code
Grep --pattern="createTerminal" --output_mode="content" --path="src/"
# Check for synchronous operations (potential blocking)
Grep --pattern="(?<!await )fs\\.readFileSync|execSync" --output_mode="content"
# Analyze addon loading patterns
Grep --pattern="new (Fit|WebGL|Serialize|WebLinks|Search)Addon" --output_mode="content" --path="src/webview/"
Common Bottlenecks:
- ✅ Synchronous file operations during creation
- ✅ Addon loading without lazy initialization
- ✅ Excessive message routing setup
- ✅ Missing dispose handler registration
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.
- 9d ago First seen · 573 lines · 43 tokens per session scan A c5ff7a3c2cf6
terminal-performance-analyzer is an agent published in the GitHub repository s-hiraoku/vscode-sidebar-terminal (21 stars, last pushed yesterday), licensed MIT. It adds 43 tokens to every session and 3,824 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-01.
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