This is mostly out of curiosity, but maybe the discussion will lead to some changes.
Going back at least several point versions of L7, perhaps back to 7.0, indexing has behaved differently than in previous releases. The indicator progresses along percentage-wise at a fairly consistent rate. When it reaches 99%, however, things change: a) CPU usage goes to nearly 100%; b) it stays at 99% much longer than at any other percentage during the cycle. Of course, that implies that when it reaches 99%, it's really only ~25-50% done (at least as measured by wall-clock time).
Note that I observe this on both a Windows 10 laptop (4th gen Core i7, 8GB, 256GB M.2 SATA SSD) and a Windows 10 workstation (4th or 5th gen Core i7, 32GB, 512GB Samsung 850 Pro SSD).
Is this the expected behavior for indexing in the latest point releases of L7? If so, is there an explanation (again, mostly curiosity)? If not, can this be corrected? At the very least, it would be nice if the percentage value matched the user's expectation of what it means.