Topic says it all, but here's the context:

My Steam webpage has been loading like I was on 56K dial-up since July, and it was only getting worse. I even reached out to Steam support but that didn't help much.
Then, ten minutes ago, I saw an error message saying my browser couldn't load Java scripts. I immediately asked myself, “Wait... when was the last time I updated Java?”

Turns out my Java version was from two years ago! That was THE problem. My Steam webpage loading speed immediately went back to normal after updating it.

So, if your Steam webpage has similar issues, just go update Java - clearing download caches and such is all nonsense.