On Windows 10, second gen Core i7 with 24GB of RAM using Lightroom 6.1.1. Trying to stack a little more than 1000 photos. Lightroom becomes unresponsive at first, then appears to have completed the task, then according to the Task Manager ~16% (4 cores hyper threaded) CPU utilization, 2.3GB of RAM used, no hard drive activity. This last for hours if I let is sit (watched a movie). Exiting Lightroom, it disappears and continues to consume CPU until I kill it. Start up Lightroom again and no stack take place. Tried this multiple times. Tested with a clean catalog as well.
There is no published number regarding a maximum number of photos that can be stacked into a single stack.
2 hours just was not a long enough wait to stack 1000+ photos. Needed to wait through a sleep cycle. At least once the photos are stacked, the stack is expandable and collapsable at a reasonable rate.
Thanks for your input.