@xyzzy thanks for the link and you're right. It's "software only" rendering. Some of the "problems detected" show:
Intel HD 3000 driver crashes frequently on Mac: 592130, 661596
Disabled Features: flash_stage3d, gpu_compositing, gpu_rasterization, flash3d, accelerated_webgl2, accelerated_2d_canvas, accelerated_video_decode, accelerated_webgl, flash_stage3d_baseline
Some GPUs on Mac can perform poorly with GPU rasterization. Disable all known Intel GPUs other than Intel 6th and 7th Generation cards, which have been tested.: 613272, 614468
Disabled Features: gpu_rasterization
Rendering artifacts on older macOS releases and Intel GPUs: 794819
Disabled Features: accelerated_2d_canvas, gpu_rasterization
I'll try an override and keep a careful eye. Thanks again.