Xref list perf improvements
Xref list perf improvements

Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api