Introduction · Performance Testing 101
What is Performance Testing?
Performance testing evaluates how well an application performs under different levels of
user load, stress, and traffic conditions.
The goal is to understand the system's speed, stability, scalability, and resource usage before it goes live.
⚙️ A type of Non-Functional Testing — not what it does, but how fast & stable it behaves
🎯
Performance Testing is a process of testing an application to determine
how it behaves when multiple users access it simultaneously,
and how quickly it responds.
👥
User Load
How many concurrent users can the system handle without degradation?
⚡
Response Time
How quickly does the system respond to user actions under load?
📊
Throughput
How many transactions or requests can be processed per second?
🖥️
Resource Usage
How effectively are CPU, memory, database, and network utilized?
Scenario
E-Commerce App — "Add to Cart" Function
How does the website behave when 1,000 users click "Add to Cart" at the same time?
⏱️
Response Time
1.2 seconds
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Server CPU
75% under load
⚠️
Error Rate
3% at 1,200 users
🔍 Common Bottlenecks Identified
Database Slow Queries
High CPU Usage
Insufficient Memory
Bad Code Loops
Network Latency
Low Throughput
Without performance testing, users may face critical issues — especially during peak traffic like sales, festivals, and promotions.
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Slow Page Loads
Users abandon sites that take > 3 seconds
⏳
Timeouts
Requests never complete under heavy load
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Application Crashes
Unhandled load spikes bring systems down
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Business Loss
Revenue lost during peak traffic events