Thanks Tom, computer / Corona version below. Scene-wise attached is the frame before it starts having the issue, no bloom and glare, no extra plugins. Just some primitives, cloners, and extruded stuff, pretty straight forward scene I thought.
Full-speed non-debug version
Build timestamp: Jul 3 2019 10:49:57
Version: 4 hotfix 1 (core 4 (Hotfix 1))
Cinema version: R20.059 CINEMA 4D Studio (single-license)
MAC OS High Sierra 10.13.6 (17G65)
Model Name: Mac Pro
Model Identifier: MacPro6,1
Processor Name: 12-Core Intel Xeon E5
Processor Speed: 2.7 GHz
Number of Processors: 1
Total Number of Cores: 12
L2 Cache (per Core): 256 KB
L3 Cache: 30 MB
Memory: 64 GB