The initial DDoS attack resurfaced "in a different form" sometime this morning, once again affecting site-wide performance. "The good news is that we were able to mitigate it quickly and performance returned to normal around 11:15 UTC. We are continuing to monitor the situation closely," WordPress announced on its "Automattic" site.
It's still unclear who's behind the attacks, which WordPress founder Matt Mullenweg called "the largest and most sustained" the service has seen in its six-year history. Mullenweg suspects the DDoS attacks may have been politically motivated against a non-English blog, but the company is still investigating and doesn't have a definitive answer yet.