I started having problems with viewing the site in 2013, too. Good to see here that it wasn't only me.
The 2013 upgrade did add things I liked, so I'm not ready to say go back to before then. I would rather see 2013 improved for viewability on high horsepower graphics machines.

I logged my 2013 viewing issues but nothing changed. I 'sorta' solved most of my viewing problems by resetting the displayed screen size to 80% of normal in the browser tool bar.

This 2015 re-do, however, is unworkable for me. I took some screen captures in another thread titled, "What I see when I come to the Renderosity SIte"

https://www.renderosity.com/mod/forumpro/?thread_id=2893190

to show how the site is presented to my machine. I tried to keep it light, stepping through some of the decisions I quickly make when trying to see what's new.

If anyone wants to add screen captures of what they see, they can do it there, especially if it is different from what I see. It might be helpful to the Renderosity team, too. I expect some machine/browser combinations may be better than mine (I can hardly imagine how they could be worse).