FastAPI installation and setup - Performance & Optimization

Performance: FastAPI installation and setup

MEDIUM IMPACT

This affects the initial server startup time and the responsiveness of the API during the first requests.

Setting up FastAPI for a new project

FastAPI

pip install 'fastapi[all]'

# Running server with reload for dev
uvicorn main:app --reload

Installs all recommended dependencies at once and runs uvicorn with reload for faster development and better feedback loop.

📈 Performance Gainreduces startup time; better dev feedback loop

Setting up FastAPI for a new project

FastAPI

pip install fastapi
pip install uvicorn

# Running server with default settings
uvicorn main:app

Installing packages separately and running uvicorn without performance options can delay startup and increase response latency.

📉 Performance Costblocks server startup for extra seconds; no async optimizations enabled

Performance Comparison

Pattern	Startup Time	Request Handling	Concurrency Support	Verdict
Separate installs + default uvicorn	Longer (5+ seconds)	Slower initial responses	Single worker	[X] Bad
All-in-one install + uvicorn --reload	Faster (2-3 seconds)	Faster responses	Single worker + reload	[OK] Good

Rendering Pipeline

FastAPI setup impacts the backend server's readiness to handle requests, which influences how quickly the browser receives data to render.

→Server Startup

→Request Handling

→Response Delivery

⚠️ BottleneckServer Startup time and initial request processing

Core Web Vital Affected

LCP

This affects the initial server startup time and the responsiveness of the API during the first requests.

Optimization Tips

1Install FastAPI with all dependencies using 'fastapi[all]' to reduce setup overhead.

2Run uvicorn with multiple workers to improve concurrency and response speed.

3Use development options like --reload for faster feedback without sacrificing performance.

Performance Quiz - 3 Questions

Which installation method helps reduce FastAPI server startup time?

A Installing only FastAPI without Uvicorn

B Installing all dependencies at once using 'fastapi[all]'

C Installing FastAPI and Uvicorn separately

D Installing Uvicorn only

DevTools: Network

How to check: Open DevTools, go to Network tab, reload the page or make API calls, and observe the time to first byte (TTFB) and response times.

What to look for: Lower TTFB and faster response times indicate better backend startup and request handling performance.