In the last days before the botched October 1 launch of President Barack Obama’s healthcare website, the team in charge was seeing alarming results from performance tests, according to internal emails released by Republican lawmakers investigating the rollout.

HealthCare.gov was unable to consistently handle 500 users at once in the testing, and tests failed with 2,000 users over a three-day period, according to a series of emails between members of the information technology team at the Centers for Medicare and Medicaid Services, or CMS.

“I do not want a repeat of what happened near the end of December 2005 where Medicare.Gov had a meltdown,” Henry Chao, the website’s project manager at CMS, wrote in capital letters in an urgent message on September 26 to his team and contractors.

Chao was referring to the disastrous launch of the Medicare Part D prescription drug program under President George W. Bush’s administration. Technical woes prevented many seniors from initially gaining access to the website.