And not by some negligible margin either. Optus has absolutely decimated the competition with speeds that frequently doubled those offered by others.
On average in Australia, Optus offers download speeds of 84.43Mbps and upload speeds of 38.15Mbps. It's closest rival, Telstra, can only manage an average download speed of 40.24Mbps and uploads of 4.38Mbps.
A mixed lag
Lagging further behind are iiNet in third place (31.21Mbps), TPG in fourth (27.04Mbps), and Dodo in fifth (14.29Mbps).
Speedtest puts Optus' dominance down to its "recently upgraded its cross-continent wholesale fibre network with Alcatel-Lucent wavelength technology to provide capacity of up to 100Gbps."
Optus doesn't perform as well in all of Speedtest's city-specific tests. TPG comes out on top in Sydney with downloads of 89.56Mbps, but Optus is a close second with 85.72Mbps.
Melbourne sees Optus storm ahead, with downloads sitting at 179.33Mbps, while TPG's 85.69Mbps has it sitting in second place. Telstra's measly 35.89Mbps meanwhile has it wallowing in fourth.
It's not all bad news for Telstra, though. The telco's been acknowledged by Speedtest as having Australia's fastest mobile network (average downloads of 37.58Mbps), followed by Optus (31.13Mbps), and Vodafone (29.52Mbps).
Telstra remains in the top spot for each of the capital cities, but Vodafone leapfrogs Optus when testing moves into Australia's urban centres.
Speedtest says Australia's largest telco has nabbed the top spot thanks to a "focus on keeping the 4GX network world-class" while investing in "next-gen technology, such as VoLTE calling and 600mbps-capable mobile hotspots."