Orcon, Telecom and Xnet are offering customers consistent broadband performance across the country, while TelstraClear users in Auckland get a better run than those in other parts of New Zealand, according to testing service TrueNet.
In its latest report, TrueNet examined internet companies' performance in Auckland and compared it with performances in the rest of New Zealand.
The tests, done during December, found that Telecom, Orcon and Xnet had a consistent performance across the country.
TrueNet measured "performance" by comparing the speeds during heavy periods of internet use (in the evening) as a percentage of those offered at off-peak times.
Telecom, Orcon and Xnet's speeds during peak periods were above 95 per cent of their speeds during periods of low demand in both Auckland and other parts of the country.
On the other hand, TelstraClear was strong in Auckland - with peak-time speeds at 97.3 per cent of off-peak speeds - but had a far worse performance elsewhere.
Christchurch-based Snap had the opposite problem to TelstraClear.
"Their Auckland performance is much lower than the rest of New Zealand, probably due to capacity constraints to Auckland," TrueNet said.
But a spokesperson from Snap questioned TrueNet's tests:
"That doesn't match up with our own internal test results. We certainly don't believe it's a capacity issue at all, as we have significant national backhaul capacity in place and significant infrastructure in Auckland," Snap's general manager of retail James Koers said in an email.
Vodafone had the worst performance in all parts of the country, the testing service said.
Vodafone offered customers in Auckland peak speeds that were 88.1 per cent of off-peak speeds and customers in the rest of the country experienced peak speeds that were 86.8 per cent of their off-peak counterparts.
All of TrueNet's tests were done in the copper-line market and did not include either fibre connections or TelstraClear's coaxial cable service, which is available in Wellington in Christchurch.