as has been explained by Tomas. GT ids being targeted by DDoS attacks. The purpose of these is overload the servers and cause the site to slow down or completely freeze.
Whilst measures can be put in place to block these attacks, hackers often find another way round so it's likely to keep slowing up until they get bored of attacking the site.
Why they are targeting GT is a bit baffling unless they are trying to extort money