How you can dramatically speed up your Django site with Django’s cached template loader

Written by andrewwidjaja | Published 2017/04/27
Tech Story Tags: web-development | django | profiling | python | performance-testing

TLDRvia the TL;DR App

I was profiling a Django 1.8 site when I noticed something peculiar.

The function django.template.engine.get_template was called 50 times and took a cumulative time of 229 ms, almost half the page load time.

The site uses a lot of template tags to render different elements on the page, such as ad positions and related story boxes.

Django’s template system will read and compile a template every time it is rendered. This happens quickly, but when you render multiple templates on each page it can add up, just like in my case.

After searching around for a solution I discovered django.template.loaders.cached.Loader, which when enabled stores compiled templates in memory, reducing the time to retrieve templates.

Once cached template loader was enabled on the site the cumulative time of django.template.engine.get_template went right down to 1 ms, reducing page load times by ~200 ms.

Cached template loader was introduced in Django 1.2, but wasn’t enabled by default and it can be quite easy to miss.

Before you enable cached template loader you will need to ensure that all your custom template tags are thread-safe.

Starting from Django 1.11 cached template loader is enabled by default when the setting DEBUG is set as False.

If you are still on an older version of Django and use a lot of template tags, enable cached template loader, it can speed up your site tremendously.

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Published by HackerNoon on 2017/04/27