Even it's slow, you can run multiple agents. You can have one doing changes, while another writes documentation, while another does security checks, while another looks for optimizations. Persist finding to markdown files to track progress and for cross-agent knowledge sharing if need. And do whatever else while it's all running. This has been my experience.
If you set up your agents correctly, they can run for hours. My record is around 4 hours for a "prod/launch readiness" on a 90k LoC codebase, and that same codebase had a marathon lint and mypy plan that fixed ~700 issues over 6 hours (split around 3/3 due to API limits)
