Telecom stole the top spot from Vodafone during June and offered the fastest web-browsing speeds over copper internet lines, according to broadband testing service TrueNet.
While Vodafone lead the market in this area from December to May it was pipped at the post by Telecom in June, TrueNet's performance graphs show.
Both internet companies downloaded TrueNet's test web page in under half a second.
Wellington internet provider Actrix was a new entrant to the tests and also ranked among the top performers.
Both Slingshot and Orcon's performance in the web-browsing tests worsened slightly between May and June, with the latter coming in last out of nine other internet providers.
While Telecom led the copper-line market, TelstraClear's coaxial cable network - available only in Wellington, Kapiti and Christchurch - still offers the fastest service.
TrueNet's measurements are drawn from 250 test sites around New Zealand, probing the speed and performance of nine interent companies