Hmm, yes I think this is probably lag from the web build sadly. Web build might have to stay in a demo state while final build is download only due to the size. I was able to run it fine on my devices but I also have a decent connection I think?
haha thats one way to put it ^^ I also tried to clean my browser's history and that kinda helped me to at least run the web engine so perhaps that would be helpful for you?