Moving iPhoto Library to Photo (Yosemite)

I just migrated all my files from my old iMac (running iPhoto 8) to my new iMac, which has a Yosemite operating system. While doing the initial setup of the new iMac, I was prompted to move my iPhoto library into Photo. I have a big library -- a little over 100GB. I did as prompted, and it's saying "Preparing Library... 3% Completed." But it's been saying that for about 2 hours! Is this normal for a library this size? Or is there something else I should be doing (or a quicker way?)

Thanks in advance! Carol