Chapter 1 · Computer Networks
1.12Network Performance
How well a network works: bandwidth (how much data it carries), latency (how long data takes) and the common causes of delay.
Written and checked by Muhammad Raheel(opens in a new tab)
Full Stack Developer · AI Engineer · Reviewed 21 Oct 2026 · 2 min read
On this page
Some days a video call is smooth. Other days the picture freezes and voices arrive late. The difference is network performance.
Good performance gives fast, smooth communication. Poor performance gives slow internet and delays. Two factors matter most: bandwidth and latency.
Network Bandwidth
Think of a water pipe. A wide pipe carries more water each second than a thin one. Bandwidth is the width of the network's pipe.
Bandwidth is usually measured in Mbps, which means megabits per second. Higher bandwidth means faster data transfer. All devices on one connection share the same bandwidth. So when many devices are busy, each one gets less, and low bandwidth makes the internet slow.
Network Latency
Latency is not about how much data moves. It is about how long one piece of data takes to arrive.
Latency is measured in milliseconds (thousandths of a second). Low latency means a fast response. High latency causes lag. Online games and video calls need low latency, because every action must reach the other side at once.
| Bandwidth | Latency | |
|---|---|---|
| What it measures | amount of data in a given time | time taken by data to travel |
| Unit | Mbps | milliseconds |
| Better when | higher | lower |
Causes of Network Delay
The book lists five reasons for network delay:
- Too many users can slow the network.
- Poor-quality cables can cause delay.
- Long distance between devices increases delay.
- Network congestion affects data speed.
- Hardware problems also cause network delay.
Congestion means too much traffic on the network at the same time, like a traffic jam on a road.
The book's class activity asks you to find the causes of delay in a given situation.
Practice this topic
Short questions
1.What is network performance?2 marks
Answer
From the book: "Network performance means how well a network works. It shows the speed and quality of data transfer." "Network performance depends on many factors, such as bandwidth and latency."
2.Define network bandwidth. In which unit is it usually measured?2 marks
Answer
From the book: "Network bandwidth is the amount of data sent in a given time. It shows how much data a network can carry. Bandwidth is usually measured in Mbps." Note: strictly, bandwidth is the maximum amount of data a link can carry in a given time (its capacity); the amount actually sent is called throughput.
3.What is network latency? In which unit is it measured?2 marks
Answer
From the book: "Network latency is the time taken by data to travel. It is the delay between sending and receiving data. Latency is measured in milliseconds."
4.Differentiate between network bandwidth and network latency.3 marks
Answer
Bandwidth, from the book: "Network bandwidth is the amount of data sent in a given time." It "is usually measured in Mbps" and "Higher bandwidth means faster data transfer." Latency, from the book: "Network latency is the time taken by data to travel." It "is measured in milliseconds" and "Low latency means faster response."
5.Why do online games and video calls need low latency?2 marks
Answer
From the book: "Low latency means faster response. High latency causes lag and delay. Online games and video calls need low latency." So low latency gives them a fast response without lag.
6.Write any four causes of network delay.3 marks
Answer
From the book: "Too many users can slow the network. Poor-quality cables can cause delay. Long distance between devices increases delay. Network congestion affects data speed. Hardware problems also cause network delay." (Any four.)
7.What is the difference between good and poor network performance?2 marks
Answer
From the book: "Good performance allows fast and smooth communication. Poor performance causes slow internet and delays."
Long questions
1.What is network performance? Explain network bandwidth, network latency, and the causes of network delay.8 marks
Answer
- Network performance (verbatim): "Network performance means how well a network works. It shows the speed and quality of data transfer. Good performance allows fast and smooth communication. Poor performance causes slow internet and delays. Network performance depends on many factors, such as bandwidth and latency."
- Network Bandwidth (verbatim): "Network bandwidth is the amount of data sent in a given time. It shows how much data a network can carry. Bandwidth is usually measured in Mbps. Higher bandwidth means faster data transfer. More devices use more bandwidth. Low bandwidth can cause slow internet speed."
- Network Latency (verbatim): "Network latency is the time taken by data to travel. It is the delay between sending and receiving data. Latency is measured in milliseconds. Low latency means faster response. High latency causes lag and delay. Online games and video calls need low latency."
- Causes of Network Delay (list): too many users; poor-quality cables; long distance between devices; network congestion; hardware problems.
- A good answer contrasts the two units: Mbps (bandwidth) and milliseconds (latency).
Aim for 250-350 words.
In this chapter
- 1.1Introduction to Computer Networks
- 1.2Network Architecture and Basic Concepts
- 1.3Types of Computer Networks
- 1.4Networking Devices
- 1.5Network Topologies
- 1.6Network Models and Layers
- 1.7Network Protocols and Services
- 1.8IP Addressing and Subnetting
- 1.9Home Network Setup and Configuration
- 1.10Wi-Fi Security and Router Configuration
- 1.11Network Diagnostic Tools and Commands
- 1.12Network PerformanceYou are here
- 1.13Network Load Balancing
- 1.14Network Security
- 1.15Data Backup and Recovery
- 1.16Usability and Security Tradeoffs