Latency vs Bandwidth: Two Reasons a Website Can Feel Slow
Why can a website feel slow on a fast connection? Delay and data-transfer capacity are different parts of the journey.
1:47 · No narration: the video shows each step as text on screen, and every step is written out below, with buttons that jump the video to it.
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The six points in the video
This is a silent video. The headings, explanations and labels below reproduce the information on screen.
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Step 1: Latency is the delay
It describes how long a response or transfer takes to begin or travel.
On-screen labels: Travel delay; Response delay; Waiting time.
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Step 2: Bandwidth is capacity
It describes the amount of data a connection can carry over time.
On-screen labels: Transfer capacity; Data per second; Connection limit.
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Step 3: Large files need more transfer
Heavy images and downloads can take longer on limited connections.
On-screen labels: Large images; Video files; Download size.
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Step 4: Many requests can add work
Several dependent requests may introduce repeated waits.
On-screen labels: Request sequence; Dependency chain; Added waiting.
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Step 5: Real conditions vary
Distance, congestion and device work affect the experience too.
On-screen labels: Network route; Busy connection; Device performance.
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Step 6: Test the customer experience
Review important pages on realistic devices and connections.
On-screen labels: Loading delay; Transferred data; Usable page result.
A practical check for your business
Describe the problem a customer experiences before choosing a network measure. A delayed first response and a slow large download may need different investigation, even when both feel like a slow site.
Sources and further detail
Common questions
Why can a website feel slow on a fast connection?
Delay and data-transfer capacity are different parts of the journey. Measure the delay and the amount of data.
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