But specialists said weeks of additional work lie ahead, including a major reconfiguration of the computer hardware, if the $630 million site, Healthcare.gov, is to accommodate the expected flood of people seeking to buy health insurance. Without the additional changes, experts predict, the website may continue to crash during periods of peak use…

One expert said the site needs to be able to handle 100,000 simultaneous users to provide a safe margin of error. “Think of it as Version Two,” he said.

Tests conducted this week for The New York Times by a California-based company that evaluates websites for major commercial clients found that the site remains too complicated for many users, and is still prone to errors and delays…

Other critical components of the site also remain to be finished, including a financial management tool to handle payments to insurance companies for customers eligible for subsidies.