Slow Dequeueing Process

We're experiencing extremely slow dequeuing of one of our sites. The following snippet from verbose logging shows that it takes almost 3 minutes to lookup visitor. This worked well for a few weeks, but has slowly declined over time.

[2020-08-31 16:01:01] piwik.DEBUG: Executing Piwik\Plugins\CoreHome\Tracker\VisitRequestProcessor::processRequestParams()... [] {"class":"QueuedTracking","request_id":31138}

[2020-08-31 16:01:01] piwik.DEBUG: token_auth is authenticated in cache! [] {"class":"CoreHome","request_id":31138}

[2020-08-31 16:01:01] piwik.DEBUG: DoNotTrack support is not enabled, skip check [] {"class":"PrivacyManager","request_id":31138}

[2020-08-31 16:01:01] piwik.DEBUG: Matching visitors with: visitorId=2f89489d694097e4 OR configId=1522d51efd5641cb [] {"class":"CoreHome","request_id":31138}

[2020-08-31 16:02:50] piwik.DEBUG: The visitor was not matched with an existing visitor... [] {"class":"CoreHome","request_id":31138}

Start at Piwik\Plugins\CoreHome\Tracker\VisitRequestProcessor::processRequestParams() and trace the queued-tracking path around the visitor matching log messages. Use the verbose log timing as the reproduction signal, then determine what causes the lookup to take nearly three minutes and verify that dequeuing no longer shows that delay.