Over the weekend, a bug popped for many Civilization VI owners resulting in the game seemingly locking up during loading screens. Thankfully, there's now a fix for it. As turdas points out, it seems like the problem was related to Windows Defender, with the program wanting to scan Civ VI every time you booted it up. This resulted in long loading times while this was done, so long that many people assumed it was a freeze and would restart their game (I clocked one wait at around eight minutes, which is crazy).
The fix is simple: Just go into your Windows Defender settings, go to EXCLUSIONS, click "add an exclusion" down the bottom then enter CivilizationVI.exe. That will exclude the game from the checks, and your load times will be back to normal.