BHphotovideo website is crippling Safari 11.0.3

This is what happens on my system trying to surf bhphotovideo website on Safari:

I noticed Safari going way too slow, to the point of total STOP with BeachBall to go with it.

Opening the Activity Monitor revealed Safari Networking sucking-up all the memory available and overwhelming the CPU resources.

No such slow down happens with Firefox. Puzzling...