[Dev]Identify _wait_for_stable_network as Performance Bottleneck

[HongxiaoN]

Pull Request: Identify _wait_for_stable_network as Performance Bottleneck

Summary

Instrumented per-step timing logs in

_wait_for_page_and_frames_load

• Instrumented per-step timing around _wait_for_stable_network
• Observed repeated hits of full maximum_wait_page_load_time (20s) on nearly every step
• Noted other stages (_check_and_handle_navigation, asyncio.sleep, _update_state) take <1s each
• Concluded that the custom network‐idle wait is the dominant contributor (>80%) to end‐to‐end latency