I've been having a lot of trouble with restoring courses as well. I don't even get a progress bar...just chugs away for a while after clicking perform restore. I'm on Windows 2012R2 with SQL Express 2012 and PHP 5.4 (as there aren't MS drivers for 5.5). The course I was trying to restore only had a couple PDF's, URL's, and 7 topics containing 7 or 8 quizzes (<2MB backup file). I did find a round-about way to get it to work which I explain in this post.
As for your comment on caching, I don't use the OPCache as it is in PHP v5.5 and MS doesn't make the SQL drivers yet, so I don't think that's the problem.
Not sure if there's anything else I can do at this point. Hopefully the restore issues will get resolved soon.
Thanks for all your help and contributions.