No it won't be faster and you will lose a lot of new features like Dx12 for example.
The only gain you could have is from getting rid of accumulated crap software that's boggin down your system but you can do that by re installing windows 10 as well.
Windows 7 is literally less than month from end of life, meaning no more security updates. Mainstream support ended nearly five years ago. Outside of niche uses, Windows 7 is over.