Extreme slowness and other issues on Windows 8.1

I just got SketchUp Make for Windows 8.1 because my school was using it. It did not work like I was expecting.
Here are 2 problems I found
1: Extreme Lagginess: One of the main reasons why i got sketch up was to see the downloads people made. When I downloaded something, it took a really long time to load and it was either placed somewhere i didn’t want to, or just basically not show up. Also, when I try to click on something else while the download was doing it’s job (because I’m sometimes really impatient), it would cause SketchUp to freeze.
2: Denied to certain downloads: I love SketchUp’s downloads and would love access to almost any of them, but the 3D warehouse won’t let me get to certain downloads. I feel like that’s not fair.
Well I think that’s all I have to say