You might want to check out this report of JAXB fixes from 2.1 to 2.1.10 :
http://tinyurl.com/jaxb-fixes-from-2-1-to-2-1-10
There are a few performance-related fixes in there, but you'll have to look at them to see if they are relevant to you!
Personally, I've very pleased with JAXB 2.1.10 because it contains several fixes that I contributed relating to usability/more helpful error mesages/conformance to the spec - it's a relief to know I won't have to worry about them anymore!
Roberto
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