I have the 100% CPU bug under a very different circumstance than other users here, but I will describe:
On my system, if I open the
Blue Iris console and select a clip to export with the following settings:
MP4
No audio
Re-encode to export 0 (export 0 being at stock settings, or altered settings doesn't matter)
Time-lapse selected with 10x multiplier, 30 fps
The system will begin saving the clip, using ~40-50% CPU, then creep progressively up higher and higher. With a long enough clip to save, the machine will hit 100% CPU, and even after the clip finishes rendering the Blue Iris service will continue using 100% CPU. Only nuking the service through Task Manager brings it back to Earth. This behavior is confirmed with newest version of BI, and 4.3.0. Also with newest Intel drivers from their website, as well as the stock drivers from the 1709 Fall Creator's build of Windows 10 Pro.
I've already emailed Ken about it to see if he could reproduce.