The website works here for me without any slow down so dont know what could be the issue with your connection.
You could try a simple solution by pressing f5 to reload the website which worked several times for me when I couldnt connect directly to the site and only received a blank screen.
Or if this doesnt work you can try and see if you can connect to their alternate site old.sportsbet.io
I have used this part of the site to see if I could connect to it when I have had troubles with the original sportsbet.io website in the past.
But just to be wary it is slower to get on this side of the site but your login should still work there.
That's the basic way of refreshing connection, but to those with slow internet I think it's still useless because it won't speed up the access. Probably those recommended option could help, and trying a simple sportbet.io on your browser might be working. The website has more exciting game, and I believed it won't take those effort be gone that's why the admins on this gambling site always ensure better alternatives when you encountered such services problems.