javax.vecmath creates so much garbage that it is best avoided
Unfortunately I need it for jbullet
I'd recommend you to try to use openMaLi
. Here is the conclusion
of the author of the JBullet. Though, it is rather negative, openMaLi was improved since then and is much more GC-friendly.
Also, its API is similar enough to vecmath, so I think you can easily replace the vecmath code with the openMaLi one's in the JBullet (maybe, even, at the 'Find-Replace' level), IIRC, someone's performed the similar task. I would find the links If you will be interested in. So, maybe there's the reason to try.
Btw, you can have a look at the JME's experience. AFAIK, it has its own math library and uses JBullet.