I could observe similar on a RPi3. The CPU usage of Hyperion v1 is always ~2-3%.
After a completely new installation with Hyperion 2.0.0-alpha.10 (same device), the cpu usage was also at ~50%. I have adjusted various settings but the CPU load never goes below ~8%. (Disable Boot Effect, Only DispmanX used, Capture frequency: 10, Picture decimation: 30).
Any idea why version 2 uses more than twice as more cpu as version 1? Is there another setting that reduces the CPU usage?