The viewer launches the SLPlugin executable and passes it (via a port) the plugin name (a shared object: media_plugin_*.[so|dll|dylib]), SLPlugin then loading it and passing messages back and forth between the viewer and the plugin object which is itself a loader and interface (which Dullahan is part of) for the actual media library (CEF, gstreamer, QtWebkit, VLC...). In the case of the CEF plugin, it's even more complex since libcef.so will itself launch multiple instances of a host executable (dullahan_host) and possibly a sandbox (the latter is not used by the Cool VL Viewer because it is a huge pain in the ass and only causes more troubles). Frankly, I find CEF a very poor browser, bloated, slow and complex, and I almost regret the v1.18 viewer old times, when the browser plugin was using a Mozilla library...
Not waiting for Dullahan but more likely CEF (libcef.so). It is probable that CEF got issues acquiring some lock or resource on your system...