Twitter addicts had to entertain themselves with something other than the social network and microblogging site for more than an hour Wednesday morning.

Twitter suffered a "sudden failure" and then encountered problems switching to a backup system, which left the site "largely inaccessible" for about 90 minutes, the company said.

Once notorious for regular and prolonged outages, Twitter has improved in this respect in the past year, but remains inconsistent. In August of last year, Twitter logged more than 6 hours of downtime, following a total of only 17 minutes in July, according to monitoring company Pingdom. In October, it had more than 5 hours of downtime, sandwiched between only 33 minutes in September and 22 minutes in November.

While Twitter is a free service, it has a large ecosystem of external developers whose revenue generating Twitter-based applications are affected whenever the system has performance problems.

In addition, Twitter has concrete plans to generate revenue itself, at which point it the stability of the site will affect customers, whether they are advertisers or businesses that subscribe to fee-based Twitter services.