I'm having the same issue in Nvivo 12 for Mac. Likewise I have plenty of processing power, but Nvivo can't seem to cope when I try to code at new or existing nodes and I get the spinning coloured wheel for minutes at a time. This drag is having a marked effect on my productivity. I'm currently coding a 40 minute interview (a focus group with 8 speakers, or cases) and I have so far introduced 140 nodes, but the software has been slow since soon after I began coding. In the same project I need to code a second interview of the same type and I also have two excel spreadsheets to add as datasets. I can't imagine how slow the program would run with all of this data, yet this single project only represents a third of what I need to analyse for my PhD!
Could somebody at Nvivo, or a user who has overcome this issue, please suggest a solution?