What to consider when installing Windows 7 on a Mac?

Question

Windows

Good afternoon, ladies and gentlemen!
I have a 2015 Mac mini mid-base. Used to work in Xcode, so I treat resources with savings.
Because of the approach of the session, there was an urgent need to use Windows. There are actually many reasons.
Therefore, I want to install Windows as a second axis, and use it as needed.
I look towards Parallels Desktop, as everything seems to be convenient and understandable.
The question is: will Parallels Desktop always use its resources (CPU, RAM, etc.), or only while Windows is running?
And in general, gentlemen, what is the best thing to do in my situation in order to save poppy system resources, but work normally on Windows?

Answer 1

virtual box

Answer 2

https://www.apple.com/ru/support/bootcamp/
What you need.

Answer 3

BootCamp is great and easy to migrate or install as a second Win system on a Mac. Drivers are also installed immediately.