It happened 10 times in a row, no matter the sockets' quantity. Then I refreshed the page, and it was stuck to only 4s. I retried this morning and it happened again, this time with 3s and 6s:
I just tried on Chrome, and it works fine there, I'll be able to play it! =D (now, why I didn't think of trying that, when I'm a Web integrator, is beyond me '^' )