Notification hook has noticeable delay compared to Stop hook

Description

When using hooks to play notification sounds, the Notification hook (with idle_prompt matcher) has a noticeable delay compared to the Stop hook, even though both use the same command.

Steps to Reproduce

1. Configure both hooks in ~/.claude/settings.json:

{
  "hooks": {
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "afplay -v 0.5 ~/.claude/bubble.aiff &",
            "async": true
          }
        ]
      }
    ],
    "Notification": [
      {
        "matcher": "idle_prompt|permission_prompt",
        "hooks": [
          {
            "type": "command",
            "command": "afplay -v 0.5 ~/.claude/bubble.aiff &",
            "async": true
          }
        ]
      }
    ]
  }
}

1. Run Claude Code and perform a task that completes → Sound plays immediately
2. Ask Claude something that triggers a question back (e.g., using AskUserQuestion) → Sound plays with noticeable delay

Expected Behavior

Both hooks should trigger at approximately the same speed since they use the same async command.

Actual Behavior

• Stop hook: Sound plays immediately when task completes
• Notification hook: Sound plays with a noticeable delay (feels like ~1-2 seconds) when Claude asks a question

Environment

• macOS
• Claude Code CLI

Additional Context

The delay seems to be in when the Notification event is fired internally, not in the sound playback itself (same file, same command, different timing).