Thank you for reply's. This been much helpful.
@Devin: "Have you compared the time difference between BF+BF and BF+LC, you may find that there the same or at least close and that may resolve your flickering problem. If your still wanting to render with LC and your pre rendering your animation using the multi frame incremental method try using Fly Through instead. You only need to render out the first frame for LC, make sure use camera path is checked, this method usually works for me.."
Yes, that's a good method also that I started to use in 2018 since the regular IR+LC doesn't work for me. Its really weird since its exactly the same settings as in Max 2016 - and I'm also using Local Subdivides. However; Multi frame incremental with Light Cache - Fly Through works really well in 2018 and is a lot fast compared to earlier versions of Max/Vray, so I'll stick with that when there's just static objects with a moving camera.
@ Francisco: "Brute force has advanced a lot since version 2.X and by the time you are done calculating and saving and loading Gi frames, rendering with Brute force+Light Cache may be faster.
There is a talk in Chaosgroup about not even saving Light cache when your camera is animated or objects are moving too. It will increase your per frame render time but this requires almost no setup time, and it will let you use GI with moving objects."
Yeah, I notice its a lot faster. If you happen to have a link to that thread at Chaosgroup, please share it.