Thanks for the vote, appreciate your feedback.
We use admin-ajax to bypass caches when sending CAPI events. It’s necessarily to avoid the Event ID being cached. The Event ID is used for deduplication, and needs to be unique to each pair of browser-CAPI events.
There are a few options.
1. Check if you really need admin-ajax:
Disable the option from the plugin’s main page.
Check in an incognito window if the Event ID for a particular event is different for each page refresh. If yes, you are fine.
2. If the Event ID is not different, you do need admin-ajax ON for CAPI. You can decide to increase server’s resources, or disable CAPI completely.
Unfortunately these are the only possibilities as long as we need to send both browser and CAPI events. Things will change when CAPI events will work without browser events. Facebook is not there yet.