Heavy? Hmm ... I think it's lighter
Back then when I was using Windows 8.1, startup took about 3 minutes before my PC is fully usable without hangs loads and stuff.
It only takes around 1 and a half minute for my Windows 10. So it's faster ^^
It could be faster, because there's some period of the boot showing a black screen after the logon logo. I did some research and found that I'm not the only one who have this problem.
I knew it'll probably slow down my PC if I did an upgrade with ton of stuff in my PC. So, I did format and uninstalled bloatware before upgrading.
Up until now, it's running smoothly. But I still prefer Aeroglass theme ^^

I found this tips somewhere via google search XD
very useful, indeed