Visual Studio uses 100% of Windows CPU, but Only 50% of Mac

Hi,
I am using Parallels Desktop 12 on a 15" MacBook Pro (Late 2016). The Mac has 16G memory and 2.7G Intel Core i7 CPU with 4 cores. I am using the laptop for Visual Studio 2017 development of a rather large C++ application. I have configured Parallels according to the various KB's. It it configured to use 4 CPUs and 8G of memory. I believe this makes sense since I really want all the juice to the C++ compiler. When compiling our software, VS will parallelize the C++ compiling of files, so what I normally see is 4 instances of cl.exe running (the C++ compiler), and a steady 100% CPU consumation. However, using Activity Monitor in MacOS shows that I only use apx. 50% of the CPU (the parallels process is steadily using around 400% CPU). This fits with my experience: Windows is sluggish while compiling, while all MacOS applications are responsive and fast. Since my ultimate goal is to get the C++ code compiled as fast as possible (takes about 20 minutes), I would rather the computer used 100% on that, and then I'd go get a coffee meanwhile. Right now it seems I am only using half of my available power for compiling.

Any thoughts on this are highly appreciated

Sverre