TelstraClear's weekend of unlimited data was managed well, according to a report from a company that specialises in broadband measurement.
While customers took to Twitter to complain about speeds over the weekend, TrueNet said TelstraClear performed "quite well" given the volumes of data being transferred.
TrueNet executive director John Butt said national speeds were reduced 40% for ADSL customers and 64% for cable customers.
"But overall customers remained able to surf the net and to access most services," he said.
Average speeds ranged between 3.3Mbit/sec and 7Mb/s and cable customers' internet speeds dropped to be on par with DSL because of overloading, the report said.
"The speed has reduced to the available capacity, with both technologies having equal access to capacity and thus having equal speeds," said Butt.
The overloading problems had largely been resolved by Sunday morning, but after 6pm performance degraded again.