Well… I dunno whether I understand you, but I guess you are loading huge models in a separate thread. Maybe it’s related:
[AsyncLoading vs. Cache)
Try cleaning your cache and see if it loads ok the first time.
I guess this bug is easy to solve… I just don’t know where to put the cache->consider_flush_index() without locking…
I filled this bug here:
bugs.launchpad.net/panda3d/+bug/1019599