I have a Mid 2012 Mac Pro 5,1 with 2x3.33 Ghz 6-core and a supported graphics card GeForce GTX 780. Boot ROM Version: 18.104.22.168.0. I have been using Mojave with no issues until I installed the supplemental 10.14.6 Build 18G87. After applying the update the Mac responded extremely slow (beach ball) and the finder kept freezing (Not responding). Lucky for me I have a clone of the whole system on a secondary HD which I recloned back to build 18G84. I tried several times to apply the update with different approaches like downloading the full install or just the regular update. Results were the same every time. So for now I left my Mac with the previously build (18G84) Any suggestions? is anybody else experiencing issues? could it be a hardware or software that's causing the trouble?