The White House set a deadline of Dec. 1 to improve the website.
Over the weekend, it released a report touting what it says is significant progress. Some 400 software bugs and hardware problems have been fixed, though more work is still needed.
The Administration says the site is now accessible 90 percent of the time, up from just over 40 percent in October. It can now handle 50,000 users at a Time; 800,000 a day.
At one point Monday, the site hit its 50-thousand user capacity. It didn't crash, but generated a message advising users what to do while they waited.
The site fixes have not been tested with heavy traffic and the administration is advising users to visit the site during off-peak times to avoid delays.