This patch to libplymouth2 makes the long pause go away. It perhaps hides the real problem, though: why is the client->requests_to_send list growing to many thousands of nodes in the first place? It sounds like there is a problem with the last Ubuntu patch to plymouth (0.8.2-2ubuntu2, “Don't call ply_boot_client_process_pending_requests on flush”, bug 570289).
This patch to libplymouth2 makes the long pause go away. It perhaps hides the real problem, though: why is the client- >requests_ to_send list growing to many thousands of nodes in the first place? It sounds like there is a problem with the last Ubuntu patch to plymouth (0.8.2-2ubuntu2, “Don't call ply_boot_ client_ process_ pending_ requests on flush”, bug 570289).