High CPU Usage and Power Consumption on Dev Community Pages – Root Cause and Workarounds

General Feedback & Requests
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Bug Description / Issue:

A persistent issue exists on the Epic Developer Community and documentation pages where idle tabs consume an excessive amount of CPU resources. Leaving a single documentation page open results in the almost complete utilization of a single CPU thread, leading to a continuous 15-30W increase in power consumption.

Environment & Reproduction:

This behavior is not isolated to a specific environment. It is consistently reproducible across multiple operating systems (including Windows 11 and Fedora Linux 43) and major browsers (Chrome, Firefox). Testing in private browsing environments confirms this is not caused by corrupted user profiles or local extensions.

Root Cause Analysis:

The elevated resource usage is directly caused by the js.hcaptcha.com/1/api.js script. It seems this script is running some continuous background Proof-of-Work (PoW) computations to maintain session verification. According to hCaptcha’s documentation: “Whether a visual challenge is presented or not, many other security controls are still operating on every request to make attempts to bypass it more costly, including advanced dynamic proofs of work.” (Source: https://docs.hcaptcha.com/pro/#999-passive-mode). Because browser JavaScript execution is largely single-threaded, this continuous cryptographic loop pins a single CPU thread to max, or near-max, capacity, effectively acting as a background miner as long as the page is open.

Temporary Workaround for Users:

For those experiencing high power draw/battery drain, high system temperatures, or fan noise while reading Unreal Engine documentation:

  1. Use a script blocker or ad blocker (such as uBlock Origin or NoScript), or the built-in script blocking features of your browser.

  2. Block the js.hcaptcha.com domain for the documentation site: https://dev.epicgames.com/

  3. This should immediately drop CPU and power consumption back to normal levels.

Note: The script only needs to be temporarily re-enabled when actively logging into an Epic account or submitting a form.

Suggestions for the Web Development Team:

If the team is looking for ways to reduce this client-side overhead while keeping the documentation safe from scraping bots, a few potential tweaks might include:

  • Scoped Execution: Consider loading or triggering the CAPTCHA script only during active interactions (such as logging in or submitting a post) rather than while users are simply reading static pages.

  • Passive Verification: It might be worth exploring lighter-weight, passive verification alternatives that don’t rely on continuous background processing to verify a user’s session.