Ultra Ajax Performance Guide
What is Ultra Ajax?
Ultra Ajax is a mu-plugin (must-use plugin) that intercepts chat API requests early in the WordPress boot process. Instead of loading the full WordPress stack — themes, plugins, widgets, the works — it loads only the handful of classes needed to handle the chat request, processes it, returns JSON, and exits.
The result: chat polling and message sending complete in single-digit milliseconds instead of the 200-500ms a full WordPress REST API request typically takes.
This is what makes short polling intervals affordable. Because each request skips the theme and every other plugin, the cost of a poll drops by more than an order of magnitude, so faster message delivery does not translate into meaningful extra server load.
How It Works
Installation
On plugin activation, ssc-fast-ajax.php is copied from the plugin’s mu-plugins/ directory into wp-content/mu-plugins/. WordPress automatically loads all files in this directory before any regular plugins, which is what gives Ultra Ajax its speed advantage.
Request Interception
When any request hits your server, ssc-fast-ajax.php runs before WordPress fully loads. It checks whether the request path matches one of the chat endpoints:
/wp-json/ssc/v1/poll— fetch new messages/wp-json/ssc/v1/send— send a message/wp-json/ssc/v1/session— start or resume a chat session/wp-json/ssc/v1/auto-reply— trigger an automated reply
If the request does not match any of these routes, the mu-plugin returns immediately and WordPress continues loading as normal. Admin-facing routes are always handled by the full WordPress REST API so that authentication and permissions work correctly.
Minimal Loading
For matched routes, the mu-plugin loads only the classes it needs:
SSC_DB— database accessSSC_Settings— plugin optionsSSC_Discord— Discord integrationSSC_Canned— canned responsesSSC_LLM— AI auto-replySSC_Chat— core chat logicSSC_REST— request handling
It skips the theme, all other plugins, widgets, sidebars, the admin bar, and everything else WordPress normally loads. The response is sent and die() is called before WordPress ever finishes booting.
Graceful Fallback
If the mu-plugin is missing, disabled, or encounters an error, the chat works normally through the standard WordPress REST API. It will just be slower. There is no loss of functionality — only a loss of speed.
Ultra Ajax speeds up the chat’s own REST calls, it does not cache pages. If a full-page cache or CDN in front of your site caches the /poll response, replies can appear stale regardless of Ultra Ajax. Exclude /wp-json/ssc/ from caching, see Caching and CDN Compatibility.
Auto-Update
When you visit the plugin settings page, the installed mu-plugin version is compared against the version shipped with the plugin. If a newer version exists, it is automatically copied into place. This is handled by SSC_MU_Installer::check_and_update().
Verifying Ultra Ajax Is Active
There are three ways to confirm Ultra Ajax is running:
- Settings > Status tab — The status tab shows whether the mu-plugin is installed and its version number.
- Direct URL check — Visit
yoursite.com/wp-json/ssc/v1/?is_ssc_ultra_ajax_activein your browser. If active, you will see a confirmation message: “Ultra Ajax is active, bypassing full loading of WordPress for chat AJAX requests.” The check answers only under the chat route, so it does not announce the plugin on the rest of your site. Available since 1.14. Earlier versions answered this check on any URL.
- Behaviour tab indicators — In the Behaviour settings tab, polling interval descriptions will indicate “Ultra Ajax is active” and show lower default values.
Polling Intervals
With Ultra Ajax active, default polling intervals are more aggressive because each request is lightweight:
| Polling Phase | With Ultra Ajax | Without Ultra Ajax |
|---|---|---|
| Active (user engaged) | 1000ms | 2000ms |
| Idle (after ~30s inactivity) | 3000ms | 5000ms |
| Deep idle (after ~2 min) | 10000ms | 15000ms |
All intervals are configurable in the Behaviour settings tab.
Lower intervals mean faster message delivery at the cost of slightly more server load. Because Ultra Ajax makes each request extremely cheap (a few milliseconds of PHP execution with no theme or plugin overhead), the more aggressive defaults are safe for the vast majority of hosting environments.
Enabling and Disabling
Enable
The “Enable Ultra Ajax” checkbox is in the General settings tab. It is enabled by default.
Disable
When you uncheck the setting, the mu-plugin file remains in wp-content/mu-plugins/ but returns early on every request, letting WordPress handle chat routes through the normal REST API. This avoids file-permission issues that could prevent re-enabling later.
Plugin Deactivation
When Super Speedy Chat is deactivated, ssc-fast-ajax.php is automatically deleted from wp-content/mu-plugins/. No cleanup required.
Rate Limiting
Ultra Ajax includes built-in per-IP rate limiting to prevent abuse:
| Endpoint | Limit |
|---|---|
/send | 15 requests/minute |
/session | 10 requests/minute |
/auto-reply | 3 requests/minute |
The /poll endpoint is not rate-limited since it is read-only and needs to fire frequently.
When a client exceeds the limit, the mu-plugin returns HTTP 429 (Too Many Requests) with an error message.
Troubleshooting
Chat feels slow
Check the Status tab to confirm the mu-plugin is installed and Ultra Ajax is enabled. If the status shows it is missing, try deactivating and reactivating the plugin, which triggers a fresh install.
Mu-plugin fails to install
Some hosts restrict writing to wp-content/mu-plugins/. Verify that the directory exists and is writable by PHP (typically owned by www-data or your PHP-FPM user, with 0755 permissions). If the directory does not exist, the installer attempts to create it automatically.
Mu-plugin causes issues
You can safely delete wp-content/mu-plugins/ssc-fast-ajax.php at any time. The chat will fall back to the standard WordPress REST API with no other side effects. If you need to re-enable Ultra Ajax later, visit the plugin settings page or deactivate/reactivate the plugin.
Discord messages not pushing
Ultra Ajax uses fastcgi_finish_request() (when available) to send the HTTP response to the visitor immediately, then pushes the message to Discord after the response is sent. If your server does not support fastcgi_finish_request(), Discord pushes happen before the response is sent, adding a small delay. This is normal on non-FPM setups (e.g., Apache mod_php).
The /poll endpoint is deliberately left out of rate limiting because it is read-only and needs to fire on every cycle. The write endpoints (/send, /session, /auto-reply) carry the per-IP limits instead, which is where abuse would actually cost you.
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