After upgrading from Confluence 6.4.1 to 6.7.1 the editor was no longer working and the server had permanently a very high CPU usage. Nothing could be found in the server logs.
After disabling Synchrony the system was running normal again. So this issue is related to Synchrony.
Settings in bin/setenv.sh:
CATALINA_OPTS="-Dsynchrony.port=8191 ${CATALINA_OPTS}"Environment:
macOS, java 1.8.0