Regular "brownouts" for the Internet are forecast as early as next year as cyberspace gets more crowded, says a report from Nemertes Research, a "respected American think-tank".
Computers and laptops trying to get online will soon just "freeze", thanks to consumer demand for content - growing at around 60% per year, not including rising demand from India and China - that will "start to exceed supply".
More people working online and the ever-increasing popularity of bandwidth-hungry services such as YouTube and the BBC's iPlayer are said to be partly to blame.
The "waves of disruption" are said to be expected next year, with computers "jittering" and "freezing", followed by "brownouts" where computers will go "offline for several minutes at a time".
From 2012 Nemertes Research states "PCs and laptops are likely to operate at a much reduced speed, rendering the Internet an 'unreliable toy'".
A Nemertes Research bod said: "Today people know how home computers slow down when the kids get back from school and start playing games, but by 2012 that traffic jam could last all day long".