An update on the significant progress the Visual C++ code optimizer made in the past year, focused mostly on the features released in the 15.3 and 15.5 versions:

MSVC code optimizer improvements in Visual Studio 2017 versions 15.5 and 15.3

by Gratian Lup

From the article:

Compared to VS2015 Update 3, VS2017 15.5 provides on average an 8.9% increase in runtime speed in the SPEC 2017 benchmark..