What did I do to screw up my MacBook/Reason

[boomer]

Running Reason9 on 2015 MacBook Pro with Sierra. Seem like every time I want to edit slice markers in the sequencer view it wants to "pre-calculate the target settings". It can take 10 minutes to do this on a 4 minute vocal track.

I fixed disc permissions, cleared up 40gigs of free space on the HD, shut off all other programs and wi-if. What am I missing that is causing this?

[Last Alternative]

Because Propellerhead needs to fix a lot of bugs for Mac users. Contact Support and let's make some noise. It's getting old.

[Surfeast]

From my experience Sierra still not friendly to audio . See if you can scale back to Yosemite , I have NO issues Mac (Retina 5K, 27-inch, Late 2015) 32 gb i5 fusion drive

[Data_Shrine]

I'm not sure if this is a problem with Sierra.. I know it wasn't working wonder when just released, however Ableton runs smoother on Sierra in my machine than it did on Mavericks.

As Last Alternative said, PH needs to fix a lot of bugs for Reason on macOS. Some of them are showstoppers (like the one you are experiencing).

[fieldframe]

As a counterpoint, Sierra has been excellent for me, but it was actually Yosemite that didn't like my audio driver (until Steinberg got around to making an updated one).

I don't think your problem has anything to do with audio drivers, though, since you're doing offline stuff (audio editing). It sounds like something is massively slowing down SSD access for Reason. Clearing up space would have been my first suggestion, but you already did that. Are you running Sophos or something that might need to exclude Reason from its scans?

[boomer]

Not running any extra protection programs other than that which may be running inside the MacOS. That said, is there something I may have inadvertently switched on inside MacOS that I should shut down?