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Django is a powerful web framework used in Python. The ease of use and reliable security make Django a popular choice, even amongst some of the biggest websites. However, performance issues may get in the way of allowing your user to have the best experience possible on your Django application.
Waiting times can cause users to leave if they are too high. Optimising your performance for your Django application means that users are more likely to continue using your web application. As a result, your user retention will increase if the user has a good experience with your Django application.
Let’s take a look at 10 ways you can reduce any performance issues on your Django application:
1: Database Optimisation
Paying close attention to your database is essential for ensuring that your Django application is working well. A higher number of requests to the database can lead to a reduction in performance. Enabling a persistent connection would help in lowering the number of created requests from Django applications. Optimising your database queries is one of the best things you can do for improving performance. In addition, you should keep track of the following: database triggers, stored views, functions and stored procedures.
Django automatically carries out caching in every QuerySet in an attempt to reduce database access as much as possible. That means increasing your understanding of QuerySet caching will help in writing more efficient code. QuerySet caching is different from Django caching, which we will cover below. Additionally, using QuerySets to fetch all the data in one query can allow for database operation optimisation, as QuerySets tend to only fetch the necessary data.
2: Caching
Computing a value takes up a lot of resources and time. But using a cache to save the value, and having it ready for the next time it’s needed can be very useful. Using caches will allow you to store the data in memory, avoiding any needless queries to the database and any expensive recalculations.
The Django caching framework allows for convenient usage of caches to improve performance. The code doesn’t have to re-run all the SQL queries when using caches, drastically increasing performance speed. It’s important to note that you should enable caching for different levels for better results, rather than just one level.
3: Laziness
Laziness is interrelated to caching. Whilst caching can save values to avoid recalculations, laziness delays computation until it is required. As a result, any unnecessary work is avoided until it absolutely has to be done. A benefit of Django is that there are lazy QuerySets already implemented. Django provides the ability to create a QuerySet, and only have it act when database activity is necessary.
4: Code Optimisation
One of the key principles of coding in Django is the Don’t Repeat Yourself (DRY). You should avoid coding the same object if it can be avoided. If you notice any repeated code, consider using a function. Redefining variables is also something you should avoid, along with keeping an eye out for any unused variables. Simplifying and restructuring your code will cause your performance to be more efficient. One way to do this is to use the Python profiler, which allows you to see the performance of specific lines of code. You can then restructure the section of your code that is taking up a lot of the CPU and memory.
5: Cached Template Loader
If you have certain templates that you use on a regular basis, then the cached template loader can be a great way to improve performance. This will allow you to retrieve the templates directly from the memory, instead of having to retrieve the template from the file system. This can be especially useful if you’re using multiple templates on the same page, as the saved time will add up from each template.
6: Pagination and Using Thumbnails
A common issue that affects performance optimisation is the amount of data displayed on one page. Reducing the amount of data displayed on a single page will certainly lead to improved performance. This is because the number of queries is reduced as a result. Moreover, having images in the exact required dimensions will also reduce data usage. If you display an image that is 200×200 pixels, but you use a 800×800 pixel image, this will mean additional data has to be loaded. Ensuring that it isn’t higher than that number means that the application doesn’t have to load any unnecessary data. This can be done by using thumbnails.
7: Performance Boost Using Varnish
HTTP performance accelerators such as Varnish will be able to handle thousands of requests per minute. Varnish can be a very valuable asset if your Django application is going to be receiving massive amounts of requests. It works by adding a cache layer, along with allowing you to cache memory for a specific timeframe. The key benefits of using Varnish are that it can be set up easily, and will begin to work immediately.
8: Functions that Reduce SQL Queries
As QuerySets follow the principle of laziness, there are 2 functions that can reduce SQL queries. These functions are particularly useful when your Django application is expanding and contains large amounts of datasets. Let’s take a look:
- select_related() – This function is used for selecting a single object. It is a performance booster that produces a single more complex query, meaning later use of foreign-key relationships won’t require database queries. It produces a QuerySet that will “follow” foreign-key relationships, selecting additional object-related data when its query is executed.
- prefetch_related() – In contrast to select_related(), this function is used to select a set of data, rather than just a single object. It performs a lookup for each relationship and fetches more data than to select_related().
9: Use Django Debug Toolbar
As previously mentioned, keeping track of queries in your database is vital for optimising performance. The Django Debug Toolbar is a commonly used Django package, and for good reason. It provides you with database query information, including query count and query speed. It can also give you the CPU load speed of each page, making it useful for monitoring performance optimisation. This will allow you to see which aspects of your Django application are causing performance issues.
10: Newest Version of Python and Django
Having the newest version of Django and Python can be one of the easiest ways of improving your application performance. If your Django application is already performing well, using the newest version can give your application a boost. However, this strategy is unlikely to have a big impact if your application isn’t optimised well. Follow the other advice mentioned in this guide, then try this one when you’ve optimised your Django application thoroughly.
Django is a popular and versatile framework used to produce a variety of web applications. Performance issues might get in the way of user experience, but following these tips will allow you to optimise your Django application. This will lead to reduced waiting times, and increase the likelihood that users spend more time using your application.
Raw Jam is a specialist Django and Python agency. If you’re experiencing issues, with your Django website and need advice, feel free to reach out to us we’d be happy to speak to you.
Researched and written by Saleem Maroof.