Lancashire has an extremely high rate of superfast broadband coverage, with access for 97% of homes and businesses.
Figures from independent broadband guide Think Broadband shows shows that superfast broadband coverage in the area is above the Government target of 95%.
But more than 15,000 homes and businesses have still been left without superfast download speeds of more than 30Mbps - needed for multiple internet users and some streaming services.
Many broadband users also find their experience doesn't live up to the advertised speed.
Think Broadband collects user-generated data from home speed tests, which shows the median download speed in Lancashire is 20Mbps.
Households with the fastest connections enjoy a download speed of at least 42Mbps.
But households with the worst broadband can only manage a download speed of up to 7Mbps - under the minimum speed required for a decent connection.
Think Broadband editor Andrew Ferguson said: "The last few years have seen dramatic changes in the availability of superfast broadband across the UK, but for those still to see any improvements it won't feel like that at all."
Communications regulator Ofcom defines superfast broadband as a download speed of more than 30 megabytes per second (Mbps), and decent broadband as 10Mbps.
Downloading films, using multiple Netflix accounts, streaming ultra-high definition videos, using Skype and playing online games all require superfast broadband speeds.
Although you can watch HD content on BBC iPlayer with a speed of just 3Mbps, according to Broadband Choices an internet-using family will struggle without a superfast connection - particularly at 'internet crunch times'.
Research by the Department for Digital, Culture, Media and Sport found that access to superfast broadband improves the local economy, reduces unemployment and increases productivity for businesses.
DCMS said that people with faster broadband also reported improved wellbeing, compared to those without.
In March, the Government said that by 2020 everyone in the UK would have a legal right to request a decent broadband connection.
This means homes and businesses will be able to request a connection speed of 10Mbps for downloads and 1Mbps for uploads, within a reasonable cost threshold.
However, Mr Ferguson says that in 2020, this speed will be the bare minimum that users will accept.
He said: "It is likely that households with more than two residents will increasingly find a 10Mbps connection annoyingly slow.
"The 1Mbps upload is looking even more dated," he added. "A five-minute cloud backup for a few pictures will make web browsing feel sluggish."
An Ofcom spokesperson said: "Although nine in 10 UK homes can get superfast broadband, too many people and small businesses still struggle to get a decent connection - particularly in rural communities.
"So we're implementing the Government's plan for a right to request decent broadband, and making it quicker and easier for companies to lay faster, more reliable full-fibre broadband networks."
The Government defines superfast broadband as a speed of more than 24Mbps.
A DCMS spokesperson said: "Our broadband rollout has helped make superfast speeds a reality for 19 out of 20 homes and businesses in the UK on time and under budget, and we are reaching thousands more premises each week.
"Our ambition is to deliver a full fibre broadband future for Britain which will prioritise rural areas, and we've made reliable, affordable, high-speed broadband a legal right for everyone by 2020."