Haven’t found that thread before, but I do have the same problem, and it only happen when I’m using subs, I’ll grab those logs in a sec, 100% (aka 1 full core) for just subtitle transcoding (not burning) is just too much.
EDIT: Just did exactly what ChuckPA said, but the forum only allow up to 40.000 characters, since it was more than it, I simply uploaded to pastebin.