CPU Reference Node – Active-Only Update Filtering

Purpose

1. This MU plugin modifies WordPress update behaviour so that:

Only active plugins and themes are included in WordPress.org update checks.

Installed but inactive assets are excluded from routine update payloads.

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Problem This Solves

On a reference server containing ~1800 installed plugins:

• WordPress includes all installed plugins in update checks.

• This creates very large request payloads.

• Admin visits trigger delayed update checks (due to deferred WP-Cron).

• Result: 3–4 second blocking delays in admin.

This is inefficient for a curated reference node where:

• Only ~10 plugins are active at any time.

• Installed ≠ in use.

• Developer-triggered update checks should be fast and predictable.

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Design Principle

Convert update behaviour from:

Installed assets = update burden

to:

Active assets = update burden

This aligns update cost with actual runtime state.

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What The Plugin Does

Intercepts outbound HTTP requests to:

• api.wordpress.org/plugins/update-check

• api.wordpress.org/themes/update-check

And prunes payloads so they include:

Plugins

• Only currently active plugins.

Plugin Translations

• Only translations for active plugins.

Themes

• Only active theme + parent theme.

Theme Translations

• Only active theme + parent theme translations.

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What It Does NOT Do

• Does not disable updates.

• Does not modify update transients.

• Does not affect plugin activation.

• Does not affect admin UI.

• Does not affect front-end behaviour.

• Does not touch core update logic.

• Does not modify installed plugin registry.

• Does not interfere with private plugin update systems.

It only reduces outbound payload size.

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Performance Outcome

Before:

• ~3–4 second admin update delay.

• Large plugin payload (~1800 entries).

• Repeated heavy update checks on admin access.

After:

• Sub-1 second update page load.

• Plugin update call reduced to ~500ms.

• Translation and theme overhead reduced further.

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Why This Is Safe

• Scoped only to specific update endpoints.

• Defensive decoding (JSON + serialized fallback).

• Early return on unexpected formats.

• Fully reversible (delete MU file).

• No database schema changes.

• No persistent side effects.

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Intended Environment

This configuration is designed for:

• Development / staging servers.

• Curated plugin reference nodes.

• Large asset repositories.

• Low-traffic environments where WP-Cron is deferred.

It is not intended for general public production sites without review.

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Future Considerations (Optional)

Possible future refinements:

• Extend update transient lifetime on dev servers.

• Trigger manual update checks on activation.

• Add Update URI: false to private plugins.

• Introduce scheduled batch scanning for inactive assets.

None of these are required for current stability.

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Removal

To revert to stock WordPress behaviour:

1. Delete the MU plugin file.

2. Reload admin.

No further action required.