are there any advantages to using tomcat 8.5.xx over 8.0.44 with Thingworx 8.1. I am mostly thinking in terms of tweaking performance
I'm not sure to what degree this is available in tomcat 8.0.x, but in tomcat 8.5.x enabling compression is something that can make quite a difference in performance.
Take a look at the discussion here.
-- Craig A.
To add to the information provided by @CRArko....
8.0 has reached end of life. See this posting on the Apache Tomcat site. Therefore it will not likely receive any additional security updates.
Refer to the migration guide available on the Apache Tomcat website for more information regarding differences in the product.
If one of the previous responses answered your question, please mark the appropriate one as the Accepted Solution for the benefit of others with the same question.