As the summary says, All revisions slnce and including 34284 are pathologically slow on project files - scene files that are linking to many set/character library files using linked groups. CPU utilization is also high*. Files take a long time to open, and then every interface interaction takes an equally long time, in the worst case more than a minute. dropping back to revision 34283 returns to normal interactivity.
I can't submit a test file due to the linked nature of the problem, presumably trying this on sintel files might yield similar results.

Operating system, Ubuntu GNU/Linux 10.10, 64 bit intel, dual/quad core systems with nvidia gfx.

*usually 100% of one core, in some cases going over.