HIGH CPU and Java Threads Post Upgrade to 5.10

We've noticed some rather bizarre behavior upgrading from ActiveMQ 5.5 to
5.10. We have a server with 4 cores and post upgrade we went from 40% on
average to over 90% CPU usage. We also noticed the number of Java threads
seems to have increased to over 400+:

[root [ at ] ServerName ~]# ps -eLf | grep java | wc -l
426
[root [ at ] ServerName ~]# ps -eLf | grep java | wc -l
422

Wondering if there is some sort of tuning parameter that needs to be set to
manage the number of java threads, or expire idle threads.

It appears out of all of the 400+ threads approximately 100+ are actively
consuming CPU:

[root [ at ] ServerName activemq]# cat 24979.txt | awk '$5 > 0.1 {print $0}' | wc
-l
106

So 75% of the threads are just sitting there doing nothing. Seems odd.