The average mobile broadband download speed in the UK is 1.5Mbps, according to Ofcom.
The regulator carried out 4.2 million speed tests, in conjunction with Epitiro, across the UK's five mobile networks between September and December last year.
On average, a basic web page takes 8.5 seconds to load. In areas with "good" 3G coverage, the average mobile broadband speed was 2.1Mbps, which fell to 1.7Mbps between 8 and 10pm in the evening.
O2 was named the fastest of all five mobile broadband providers, with download speeds of between 2.4Mpbs and 2.9Mbps. The mobile network also had the lowest average latency, or response time for a single data packet to travel from the device to a third=party server and back again.
"Our customers are seeing the benefit from the huge investment we have made in our network. We always aim to deliver the best network experience for our customers and these results are another indicator that we are doing just that," said O2's chief technology officer Derek McManus.
Orange came out worst, with a download speed of between 1.1Mbps and 1.4Mbps.
Ofcom's research also revealed 17 percent of UK households are using mobile broadband to access the web, with seven percent saying it's there only way of getting online, up from three percent in 2009.
However, the average mobile broadband speed is still well below the UK's average fixed line broadband speed of 6.2Mbps.
Ofcom said that while, as expected, mobile broadband speeds were faster in urban areas than rural area, due to the availability of 3G connection, in urban area performance was highly variable.
"This research gives consumers a clearer picture of the performance of mobile broadband dongle and datacards as consumers use these services to complement fixed-line services or sometimes as their principal means of accessing online services," said Ofcom Chief Executive, Ed Richards
The regulator urged mobile broadband customers to check with a provider the coverage levels before purchasing a service.
Chris Marling, editor of BroadbandGenie, said the figures make pretty depressing reading.
"Firstly, they back our feeling that the UK's mobile networks are doing next to nothing to increase speeds, as they have stalled at below 2Mbps for a long time now. It seems the networks are just waiting for the spectrum auction which will allow 4G mobile broadband networks to start rolling out."