Session-based authentication in NestJS - Performance & Optimization

Performance: Session-based authentication

MEDIUM IMPACT

This affects page load speed and interaction responsiveness by managing server-side session storage and cookie handling.

Managing user authentication state efficiently

NestJS

app.use(session({ secret: 'secret', resave: false, saveUninitialized: false }));
// resave: false avoids saving unchanged sessions
// saveUninitialized: false avoids saving empty sessions

Reduces unnecessary session writes and database or memory operations, improving response speed.

📈 Performance GainSaves 10-30ms per request and reduces server load

Managing user authentication state efficiently

NestJS

app.use(session({ secret: 'secret', resave: true, saveUninitialized: true }));
// resave: true forces session save on every request
// saveUninitialized: true saves empty sessions

Forcing session save on every request and saving uninitialized sessions causes unnecessary server load and slower response times.

📉 Performance CostIncreases server CPU usage and delays response by 10-30ms per request

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Session saved on every request (resave: true)	N/A	N/A	N/A	[X] Bad
Session saved only when changed (resave: false)	N/A	N/A	N/A	[OK] Good

Rendering Pipeline

Session-based authentication involves server-side session validation before responding to client requests, affecting the time before the browser receives content.

→Network

→Server Processing

→Response Time

⚠️ BottleneckServer Processing due to session lookup and validation

Core Web Vital Affected

INP

This affects page load speed and interaction responsiveness by managing server-side session storage and cookie handling.

Optimization Tips

1Avoid saving sessions on every request by setting resave to false.

2Use fast session stores like Redis or in-memory caches to speed up session validation.

3Set saveUninitialized to false to prevent saving empty sessions and reduce server load.

Performance Quiz - 3 Questions

What session option reduces unnecessary session saves in NestJS?

A saveUninitialized: true

B cookie.secure: true

C resave: false

D rolling: true

DevTools: Network

How to check: Open DevTools, go to Network tab, filter requests, and check response times for authenticated endpoints.

What to look for: Look for increased server response times indicating session validation delays.