Catalog upgrade in progress - preparing new searchable data

I'm making the leap from LR 4 to LR Classic CC. I started the install about 20 hours ago, and I'm stuck on the above progression box.

"Catalog upgrade in progress - preparing new searchable data" and its only gone up about 10%.

I have the internal drive and two external drives connected (not sure if that is an issue).

I'm seeing a few posts around the internet that begin with, "you should have done this before trying to install..."

That doesn't help me, my reality is that I'm not sure if anything is going on, when I bring up the process manager, LR looks like its working pretty hard.

What happens if I hit the cancel button?

Should I just let it continue to do whatever its doing?

If I do let it keep doing the catalog thing, is it going to take days, or weeks to finish?

Sorry about being a whiny baby, seems like a few people have this issue, not sure what if any are actual fixes, or if I should let LR Classic CC do its slow ride.