WordPress admin-ajax slow/issue

Question

I've noticed in our hosting's snapshot that our admin ajax has been very slow.

The example http query below took over 191seconds! also this fired every couple of minutes.. /admin-ajax.php?action=oembed-cache&post=814

apart from that just the normal admin-ajax.php takes about 15seconds. Sometimes spikes to 45seconds.

This leads to some get requests for our products to take 45seconds.

Any ideas what the cause/fix to this might be, or at least where I should look into next? Query monitor is not showing any errors only some minor notices and nothing in debug.log.

Thanks