Two people question a person writing code is not how you induce stress in a candidate nor get anything useful done. This is an unrealistic scenario that I cater for and protect people from. The most negative part was a personal / hostile technical comment. Here is both my technical and personal feedback. Test Automation has a number of components and a minor performance gain of one area is insignificant until such automation is implemented, established and scaled to a large degree which I didn't get the impression was the case. The abstract nature of code and desgin allows flexibility for later consideration without much cost even if one of the inferrior techniques are used as I explained and admitted the alternative is a better choice. With respect to this topic, what I as a person decide to learn, practice and promote in my own time has no place for discussion and comments towards this are considered as hostile in a professional environment.