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.