Thanks for the reply.
I saw the JAVA issue threads you mentioned, but it was Windows based.
When I check the Java versions on my R-Pi:
Arduino IDE 1.8.9 JAVA_VERSION="1.8.0_191" and Arduino IDE 1.8.3 JAVA_VERSION="1.8.0_121"
I will swap out the older Java with the newer. The last time I saw this 100% CPU throttle was building the core with a compile switch - j4. Changing to j1 fixed it. But, the compile and build commands, switches etc are the same for the IDE 1.8.3 and 1.8.9
tnx
sc