Dear Bruno,
I have missed your second message, sorry.
These messages are normal when you launch Cassandra the FIRST TIME. Jython builds an indexation base of all loaded/called jar files. Let this phase finish. The disk space used is very small and the directory is built in the ./ThirdPart/jython2.1/cachedir/ folder.
The next launchs will be faster and with a lower CPU cost.
Best regards,
The Artenum Team.