Some slowdowns were still affecting Internet traffic between the Far East and major Web sites in the United States. Dan Todd, chief technologist of public services for Internet watcher Keynote Systems, said some companies might still experience lost data or dropped connections.
"Certainly, for multinational companies with intranets or extranets across the Pacific, this hurts," said Todd. "E-mail, voice-over-IP and Web traffic all travels over the same fiber."
Millions of people in Taipei, Singapore, Hong Kong and mainland China were cut off from communications to the West late Thursday after a trans-Pacific cable was severed.
Around 4 p.m. PST on Thursday, data traveling between those cities and North America almost stopped: Nearly 80 percent of all data was lost and response times between computers on each side of the Pacific took, on average, 150 percent longer, according to a Keynote survey.
Traffic to and from Singapore was worst hit, with delays exceeding a minute for each packet, about 7.5 times greater than normal. Other cities saw similar delays: Times to Taipei quadrupled and to Hong Kong doubled, according to the survey.
Keynote said it could not get reliable data on Internet performance between mainland Chinese cities and the United States.
In other major cities in China, Web users said they were unable to visit overseas sites, although many domestic addresses were accessible.
"Restoring the cable will take 23 days,'' said Wang Yang, an official at the Network Management division of state phone giant China Telecom.
"We are sparing no effort to redirect traffic through other channels, but access speeds could be fairly slow,'' Wang said.
China has several undersea cables connecting its data networks to the rest of the world, but the Shanghai-U.S. line carried the most traffic, she said.
While China Telecom said it could take almost three weeks to make repairs, the Internet had apparently adapted to the problem by early Friday, when companies reconfigured switching hardware to route around the cable cut.
By Friday 10 a.m. PST, traffic slowdowns only amounted to a few seconds at most, said Keynote's Todd.
Officials said they did not know what caused the break.
Singapore Telecommunications said the cable break had slowed traffic over its networks. "We've had some traffic that goes through this cable,'' a Singtel spokesman told Reuters. "We've had to divert.''
Taiwan's state phone company, Chunghwa Telecom, also reported that a broken submarine cable was preventing ISPs from connecting to servers off the island. The company was trying to switch traffic to satellites.
Some Chinese Internet companies reported difficulties overcoming the roadblock, putting them at risk of losing page views that drive advertising sales.
Many domestic companies, for example, locate computer servers overseas.
"Our programmers have to make long-distance calls in order to work on the site,'' said Porter Erisman, marketing vice president for e-commerce portal Alibaba.com, whose programmers are based in the Chinese city of Hangzhou.
Some Web users in Hong Kong also said they experienced slower-than-usual online speeds.
"All this talk about the Information Revolution--it can all be brought to its knees by a shark,'' said Steve Yap, spokesman for Internet research firm Iamasia in Hong Kong.
While a shark is probably not the culprit, fishermen might be to blame. A report on a Chinese portal site speculated that a trawler may have inadvertently snapped the cable.
Reuters contributed to this report.