Tons of people still use QuickFIX. As I think you know, people very concerned with speed try to avoid using any kind of FIX for trading but still use QuickFIX f

Tons of people still use QuickFIX. As I think you know, people very concerned with speed try to avoid using any kind of FIX for trading but still use QuickFIX for things outside the hot path such as drop copy (duplicate stream of trades for reliability). QuickFIX is open source too, so you can make it somewhat faster without abandoning it. I did.