Heroku deployment in Ruby on Rails - Performance & Optimization

Performance: Heroku deployment

MEDIUM IMPACT

This affects the initial page load speed and server response time by how the app is deployed and served on Heroku.

Deploying a Rails app on Heroku for fast user access

Ruby on Rails

Procfile:
web: bundle exec puma -C config/puma.rb

# Use Heroku Ruby buildpack and optimized Puma config

Using Puma with optimized config and specifying it in Procfile improves concurrency and startup speed.

📈 Performance Gainreduces server startup time, lowers LCP by seconds

Deploying a Rails app on Heroku for fast user access

Ruby on Rails

git push heroku master
# No buildpacks or Procfile configured, default web server used

Using default settings without specifying a proper web server or buildpacks can cause slow startup and poor request handling.

📉 Performance Costblocks initial response for several seconds, increasing LCP

Performance Comparison

Pattern	Server Response	Asset Delivery	Startup Time	Verdict
Default Heroku deploy without Procfile	Slow (5+ sec)	Direct from dyno	High (cold start)	[X] Bad
Heroku deploy with Puma and Procfile	Fast (1-2 sec)	Precompiled + CDN	Low (warm dyno)	[OK] Good

Rendering Pipeline

Heroku deployment affects the server response stage before the browser starts rendering. Slow server response delays Style Calculation and Paint.

→Server Response

→Style Calculation

→Layout

→Paint

⚠️ BottleneckServer Response time due to dyno startup and request handling

Core Web Vital Affected

LCP

This affects the initial page load speed and server response time by how the app is deployed and served on Heroku.

Optimization Tips

1Always specify a Procfile with an optimized web server like Puma for Heroku Rails apps.

2Precompile assets before deployment and use a CDN to speed up asset delivery.

3Monitor server response times to reduce Largest Contentful Paint (LCP) delays.

Performance Quiz - 3 Questions

What Heroku deployment practice improves server response time for a Rails app?

A Deploying without precompiling assets

B Using default WEBrick server

C Using a Procfile with Puma web server

D Serving assets directly from dyno without CDN

DevTools: Network

How to check: Open DevTools > Network tab, reload page, check Time to First Byte (TTFB) and asset load times

What to look for: Low TTFB indicates fast server response; fast asset load times show good asset delivery