WordPress Heartbeat API Causing High CPU: Fix (2026)
Quick answer
The Heartbeat API polls admin-ajax.php every 15 seconds when the editor is open, which spikes CPU on shared hosts. Fix by installing Heartbeat Control (free), throttling to 60 seconds on the front-end and dashboard, and 30 seconds inside the editor. On busy sites, WP Rocket also has Heartbeat controls under File Optimization → Heartbeat.
Confirm Heartbeat is the culprit
Open your host's slow query log or New Relic. If admin-ajax.php dominates and each request POSTs an `action=heartbeat` payload, you've found it. On shared hosts this alone can push you over CPU limits and trigger throttling.
Fix #1, Install Heartbeat Control
Install Heartbeat Control by WP Rocket (free). Set: Frontend = Disable, Backend = 60 seconds, Post Editor = 30 seconds. This reduces admin-ajax.php calls by 90%+ on most sites.
Prefer we just fix it?
Runaway CPU, slow admin, and mystery timeouts are what our speed optimization service kills, Query Monitor + New Relic diagnosis, plugin swap-outs, and a documented before/after report. Learn more about WordPress speed optimization or grab a slot below.
Fix #2, WP Rocket Heartbeat
If you have WP Rocket, don't double-configure. Use its built-in Heartbeat controls (Settings → Heartbeat) and skip the separate plugin.
Fix #3, Don't disable Heartbeat entirely
Disabling Heartbeat in the editor breaks autosave and post-locking (two editors can overwrite each other). 30-60 seconds is the safe throttle, full disable only makes sense if no one edits inside wp-admin.
When to call for help
If Heartbeat throttling doesn't fix your CPU spike, the real culprit is usually a rogue plugin cron job or an unindexed autoload option. Our performance audit starts at $149 and includes Query Monitor + New Relic analysis.
Common questions
What is the WordPress Heartbeat API?+
A built-in mechanism that polls admin-ajax.php from the browser every 15-60 seconds to power autosave, post-locking, real-time notifications, and dashboard widgets. It's useful but can spike CPU on shared hosts.
How do I reduce Heartbeat CPU usage?+
Install Heartbeat Control (free) and set Frontend = Disable, Backend = 60s, Editor = 30s. This drops admin-ajax.php load by 90% without breaking autosave or post-locking.
Is it safe to disable the Heartbeat API?+
Safe on the frontend and dashboard, risky inside the post editor. Disabling in the editor breaks autosave and allows two people to overwrite each other's edits. Throttle to 30-60 seconds instead.
Why is admin-ajax.php using 100% CPU?+
Heartbeat is the usual cause on WordPress sites, but not the only one. WooCommerce cart fragments, plugin cron via admin-ajax, and popup/analytics plugins also route through admin-ajax.php. Query Monitor identifies the specific action causing the load.
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