Django devs: Your app is probably slow because of these 5 mistakes (with fixes)

Just helped a client reduce their Django API response times from 3.2 seconds to 320ms. After optimizing dozens of Django apps, I keep seeing the same performance killers over and over.

The 5 biggest Django performance mistakes:

N+1 queries – Your templates are hitting the database for every item in a loop Missing database indexes – Queries are fast with 1K records, crawl at 100K Over-fetching data – Loading entire objects when you only need 2 fields No caching strategy – Recalculating expensive operations on every request Suboptimal settings – Using SQLite in production, DEBUG=True, no connection pooling

Example that kills most Django apps:

# This innocent code generates 201 database queries for 100 articles def get_articles(request): articles = Article.objects.all() # 1 query return render(request, ‘articles.html’, {‘articles’: articles}) html <!– In template – this hits the DB for EVERY article –> {% for article in articles %} <h2>{{ article.title }}</h2> <p>By {{ article.author.name }}</p> <!– Query per article! –> <p>Category: {{ article.category.name }}</p> <!– Another query! –> {% endfor %}

The fix:

#Now it’s only 3 queries total, regardless of article count def get_articles(request): articles = Article.objects.select_related(‘author’, ‘category’) return render(request, ‘articles.html’, {‘articles’: articles})

Real impact: I’ve seen this single change reduce page load times from 3+ seconds to under 200ms.

Most Django performance issues aren’t the framework’s fault – they’re predictable mistakes that are easy to fix once you know what to look for.

I wrote up all 5 mistakes with detailed fixes and real performance numbers here if anyone wants the complete breakdown.

What Django performance issues have burned you? Always curious to hear war stories from the trenches.