What is the keyboard shortcut in Corona 4 and 5 to region render? In Corona 2-3 it was Shift in VFB. THIS was a very good shortcut and since the Corona 4 version it has been turned off :(. As for sub-sampling, it is very useful for scenes from FP, where even with a larger lawn the amount of primitives instances often exceeds 2-3 billion and Corona needs a moment to reduce it but in Corona 3 and 4 it works great and fast.
Those who are disturbed by large squares / pixels when moving objects or camera, I recommend increasing GI vs. AA balance at 32-64, (better to see the difference in scenes without FP), then it should look nicer for everyone :) to reduce Light Samples Multiplier to 1, and then they work IR even faster, I also recommend setting Secondary Solver to None, and Max ray depth at 5-10 which additionally smooth work in IR, and the quality will be noticeably worse, slightly shaded places will be darker slightly. But for quick previews and quick work with the stage, these settings are sufficient and increase the comfort of work. When working with FP, it's good for even faster GI vs. Set AA balance to 2 and Light Samples Multiplier to 7. I recommend trying it because the difference is significant.
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