If you go to https://phabricator.wikimedia.org/maniphest/report/ you get
Request aborted by debug time limit after 30 seconds.
STACK TRACE
ManiphestTask.php:153 PhabricatorStartup->onDebugTick()
ManiphestTaskQuery.php:349 ManiphestTask->attachProjectPHIDs()
PhabricatorPolicyAwareQuery.php:260 ManiphestTaskQuery->didFilterPage()
ManiphestReportController.php:409 PhabricatorPolicyAwareQuery->execute()
ManiphestReportController.php:46 ManiphestReportController->renderOpenTasks()
AphrontController.php:33 ManiphestReportController->processRequest()
index.php:103 AphrontController->handleRequest()
This was working before our Bugzilla migration, when we had less than 2000 tasks. Now we have more than 75k.