Performance metrics collection in Selenium Python

Introduction

Collecting performance metrics helps you understand how fast and smooth a website works. It shows if pages load quickly or if something slows them down.

Checking how fast a website loads after changes.

Finding slow parts of a page to improve user experience.

Comparing performance before and after adding new features.

Monitoring website speed regularly to catch problems early.

Syntax

Selenium Python

performance = driver.execute_script('return window.performance.timing')

This code runs JavaScript inside the browser to get timing data.

The 'performance' object contains many useful time points about page loading.

Examples

Calculate total page load time by subtracting navigation start from load event end.

Selenium Python

performance = driver.execute_script('return window.performance.timing')
print(performance['loadEventEnd'] - performance['navigationStart'])

Get all resource load times like images and scripts.

Selenium Python

performance = driver.execute_script('return window.performance.getEntriesByType("resource")')
for resource in performance:
    print(resource['name'], resource['duration'])

Sample Program

This script opens a website in headless Chrome, collects page load timing, calculates total load time, and prints it.

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.chrome.options import Options

options = Options()
options.add_argument('--headless')
service = Service()
driver = webdriver.Chrome(service=service, options=options)

driver.get('https://example.com')
performance = driver.execute_script('return window.performance.timing')

load_time = performance['loadEventEnd'] - performance['navigationStart']
print(f'Page load time: {load_time} ms')

driver.quit()

Important Notes

Sometimes 'loadEventEnd' can be 0 if the page is not fully loaded yet; wait or check before calculating.

Performance timing data is in milliseconds since navigation started.

Headless mode runs browser without opening a window, useful for automated tests.

Summary

Performance metrics show how fast a page loads and resources load.

Use JavaScript execution in Selenium to get performance data.

Calculate load times by subtracting key timestamps from the performance object.