Sandro Pereira wrote a blog about Windows Defender and BizTalk 2016. Well worth a read.
Why checking if Windows Defender is running on BizTalk Server, or another anti-virus, is important?
They tend to be a little slow, so tuning it well is important for archive a better performance and by default Windows Defender is configured on that machines. Not only as a negative impact in the general performance of the machine but also can have a huge impact on BizTalk Server performance.