Background subagents in Claude Code now use far less of your usage limit, Anthropic's @ClaudeDevs account posted on November 4. A running subagent updates its status line every 30 seconds, and each update used to re-read the subagent's whole conversation; now Haiku 5.5 writes the update from short notes instead, so each update costs about 99% less.

The change targets the status line, not the subagent's work itself — but at 120 updates an hour per running subagent, the old overhead added up for anyone leaving agents running in the background. Anthropic gave no token counts, and the post does not say which Claude Code version carries the change or whether it applies on every provider.