Top Causes of Poor App Performance and Tips for Fixing a Slow App

If you scroll down our blog a bit, you’ll see two infographics describing the state of the App Store and Google Play. While both of them feature several interesting insights, let’s pay attention to the number of apps in both stores: 1.96M in the App Store and about 5M in the Google Play.

These numbers clearly indicate that the mobile application industry is booming. And the basic expectation of any modern app user is seamless and frictionless app performance. So if you have a slow app and want to fix it, we assembled a list of possible solutions.

Top Causes of Poor App Performance and Tips for Fixing a Slow App

Network issues

The quality of network connectivity is something you can’t really control as an app owner but you can still improve the app’s performance in case of poor connectivity.


The use of a content delivery network is a great way to improve the performance of your software product, be it a mobile or a web application. A CDN makes use of multiple servers across the globe in order to efficiently distribute content to users. In this way, a user gets content delivered by the closest server in terms of geographical location and this method significantly improves the content transfer process.

Load data as you need it

On average, a mobile app processes great amounts of data on a regular basis. Hence, if an app tries loading a huge chunk of data at once, chances are high that it will impact the app’s performance. In order to resolve the issue, it’s recommended to load the data as you need it – in other words, breaking it down into smaller chunks. For that, you’ll need to use split assemblies that will do the job. Another piece of advice here is to load textual data first and the image-based content can be loaded asynchronously and on a second-priority basis.

Reduce the number of HTTPS requests

When there are millions of sessions going on at the same time, it significantly slows down the app performance. Hence, you can optimize what each request does in order to reduce the load and therefore speed up a slow app. Here are some things that will help:

  • Remove unnecessary images to reduce the number of requested files;
  • Reduce the file sizes (since bigger files = longer requests);
  • Implement asynchronous JavaScript loading and, if possible, combine it in one file;
  • Combine your CSS files together.

UI issues

Another possible problematic area with your slow app is its user interface and its components. While interactive and rich UI is a trend, it can significantly slow down the work of your app. So how do you balance attractive design and good performance?

Compress the content

Image (and overall content) compression is one of the most common ways to improve the app’s performance. There are two ways to do it: lossless and lossy compression.

  • Lossless compression: this method is used mostly for text and spreadsheet documents. In this method, a developer can restore a file to its original size so no data is lost during the compression.
  • Lossy compression: a developer removes the data from an app but it’s not noticeable for users. This method is widely used for image, audio, and video compression.

In addition to compression, you can also cache certain images so the app won’t have to load them, again and again, each time they are requested. 

Reuse templates

An app usually contains many data templates and every time they are needed, the app has to load them. So obviously, this impacts the app’s performance and slows it down. What you can do is simply reuse the templates to reduce the load a little and help the app load the content in a faster manner.

Server issues

Issues with a server are usually among the most common reasons behind a slow app. Luckily, the backend part of the application can be fully managed and controlled by your development team. So if you conducted a performance analysis and identified any problems on the backend part, it’s highly likely that the methods listed below will help you.

Use a reverse proxy server

An efficient way to handle the load is by using a reverse proxy server. A reverse proxy server sits in between the firewall and the machine that runs the app and handles the traffic. By being directly connected to the Internet, a reverse proxy server creates an internal network and hence provides an extra layer of abstraction. In this way, it ensures a smoother flow of network traffic a directs user requests to the appropriate server. 

Use a load balancer

If you use several small servers (a server farm) instead of a big one, you’ll need a load balancer. It is a tool used for keeping the response time low by distributing the load evenly across the servers. In addition to that, a load balancer can also assist with static file caching and termination of SSL. In terms of choosing the load balancer, it’s best to use the one suggested on your cloud platform.

Optimize TLS

On one hand, the use of TLS has now become somewhat a standard – but on the other, its use can have a negative impact on the performance of your app. Luckily, there is a solution and it’s the optimization of TLS. Here are some tips on it:

  • Choose certificates from proven sources only;
  • Optimize the TLS handshake by “domain sharding”, resource caching, or enabling persistent connections;
  • Consider the usage of HTTP/2 over TLS, when possible;
  • Deploy a CDN (as mentioned above);
  • Cache sessions.

Also note that general-purpose web applications should only support TLS 1.2 and TLS 1.3, with all other protocols disabled.Loading issues

Users expect a mobile application to load in not less than two seconds – otherwise, they grow impatient and leave with a poor user experience. Needless to say, a slow app causes poor user experience and can result in app uninstallation. So what can you do to make sure your app loads at a lightning-fast speed without harming its content?

Use caching

You are most probably aware of the importance of using caching but let’s go through it once more time. Caching means storing frequently used data in a temporary storage location aka cache and it brings the content closer to a user. 

In terms of mobile, caching allows downloading of the data from the network onto the computer’s memory. That means your app won’t have to download the requested data from the external store but will simply retrieve it from the internal memory. Needless to say, caching can increase the loading time significantly and thus leads to a better user experience.

Update the app regularly

There are several reasons why updating the app is really important. First, regular updates provide security patches to an app and contribute to safeguarding its data. And second, if the app was not updated to the latest version of the OS system, it will perform slowly (not to mention all the bug fixes that updates deliver). Note that the latest OS version of iOS is iOS 14 and the latest version of Android OS is Android 12. 

For Android apps, it’s recommended to build it with App Bundles so that Google Play can optimize the size of an update for you. An App Bundle is a publishing format that contains all your app’s compiled code and resources, and defers APK generation and signing to Google Play. iOS has the same publishing format which is iOS App Thinning and it works pretty much the same as the App Bundle for Android.

General tips

We’ve covered the major areas for improving a slow app. However, there are still a few things left to say so let’s quickly have a look at them.

Check all third-party libraries and SDKs

While your developers are in full control of the code that they write, they cannot 100% guarantee the quality of third-party libraries and SDKs that might be used for an app. However, such external tools often happen to contain different bugs and errors that can seriously harm the performance of your app in the future. To prevent any possible issues, always double-check any external tools that you use and make sure they are secure and stable.

Do real-time performance monitoring

Real-time monitoring of your app’s performance can help you quickly react to any issue detected and also identify what’s causing it. In this way, you’ll be able to proact in the future instead of reacting to occurring bugs and this will improve the performance a lot.

Shed unnecessary features

Sometimes your app performs poorly just because you over-complicated it with features. The more heavy features the app has, the slower the performance will be. Hence, if you suspect this is the reason why you have a slow app, we recommend doing a revision and checking whether you really need all the heavy features. By removing unnecessary functionality, you will make your app more lightweight and hence, more responsive and efficient.

Summing up

The performance of a mobile app directly impacts user experience so it’s in your best interest to fine-tune it and make sure the app adheres to the set quality standards. If you have any considerations related to your app or want to check whether everything is fine, you can reach out to a mobile app development company and request a performance audit. This will help you not only identify the possible issues but also detect any weak areas and the best ways to improve them.

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