Web application optimization: Best practices for improved performance


    Starting the process of optimizing web applications, it is crucial to understand that speed and smooth operation are no longer just additional advantages but basic expectations of users. Performance optimization is a continuous process, requiring both strategic planning and technical implementation. In this article, we will focus on practical steps and techniques that can be applied to significantly improve the user experience while increasing the position of your application on the internet. We will start from the basics of performance analysis, through resource optimization, to advanced caching techniques.

    The Importance of performance optimization

    Website performance optimization is crucial for online business, as it directly affects user satisfaction and conversion effectiveness. Fast page loading increases user engagement, lowers the bounce rate, which is important for front-end performance, as even seconds of delay can cause significant financial losses. Moreover, high performance improves site visibility in search engines, as SEO algorithms favor quickly loaded pages, considering them more user-friendly. This leads to better search results positions, naturally increasing site traffic and potential revenue. By investing in optimization, companies can significantly improve web application performance and site usability, translating into better SEO positions, increased user engagement, and ultimately - conversion growth and brand stabilization in the online environment.

    Analysis of slowdown sources and application resource optimization

    To optimize progressive web apps (PWAS) performance, it is key to apply an integrated data-based approach. Starting with analysis using proven tools such as Google Lighthouse, PageSpeed Insights or GTmetrix, you can get a clear picture of what slows down your site. Optimizing images, minimizing CSS and JavaScript files, and implementing lazy loading are fundamental steps that significantly affect loading speed and overall responsiveness. Monitoring the changes introduced and iteratively improving based on the data ensures continuous utilizing caching for better performance.

    Analysis process in a nutshell

    • Performance Analysis: Use tools like Google Lighthouse, GTmetrix, WebPageTest.
    • Image Optimization: Compress and choose appropriate formats.
    • CSS/JS Minimization: Reduce file size.
    • Lazy Loading: Implement for non-critical resources.
    • Monitoring and Iteration: Track the impact of changes, iteratively improve.

    Utilizing caching for better performance

    Utilizing caching can significantly speed up page loading time, improving user experience and SEO and back-end performance. Caching allows users' browsers to locally save copies of frequently used resources, reducing the need for their re-downloading on subsequent visits. Strategies such as server-side and browser caching can significantly reduce server load, translating into faster page loading, better application scalability, and web application performance tuning.

    How does server-side differ from client-side caching?

    Server-side and client-side caching differ in scope and data management. Client-side caching allows browsers to save resources, such as JavaScript files, CSS, and images, reducing loading time on subsequent site visits. In contrast, server-side caching focuses on storing frequently requested data on the server, enabling faster delivery without the need for each time processing. Both approaches reduce latency, but their effective combination can provide optimal results, increasing performance in web applications, and scalability of the application while reducing server load and improving user experience.

    Improving loading time with SSR and CSR

    In the context of improving loading time, using SSR and CSR techniques is essential, and the Next.js framework plays a key role here. With SSR, Next.js allows for server-side content generation, significantly speeding up the initial page load and improving its visibility to search engines, as discussed in the article on iMakeable. Meanwhile, CSR ensures quick interactivity after the application loads. Next.js offers flexibility in choosing between SSR and CSR, enabling the creation of performance-optimized web applications.

    If you want to learn more, read our article dedicated to Next.js – we discuss SSR and CSR there in more detail. Click here.

    Comparison of CSR and SSR:

    • CSR (Client-Side Rendering):

      • Loading time may be slower initially due to the need to download scripts before rendering content.
      • SEO may be problematic, as search engines may struggle to index dynamically generated content.
      • Better for applications requiring high user interactivity after the page loads.
      • Simpler client-side implementation, but may require additional tools for SEO.
    • SSR (Server-Side Rendering):

      • Provides faster initial page loading, as content is generated on the server side and sent to the client.
      • Better SEO support, as search engines receive ready content to index.
      • Preferred for pages where fast loading and content availability are key, e.g., blogs, news sites.
      • Requires more complexity on the server side and can affect scalability.

    Next.js offers the ability to use both application optimization techniques, allowing the choice of the best approach for a specific use case, significantly impacting the improvement of asynchronous loading time and content availability.

    Optimizing applications for mobile devices

    The next key aspect of web application optimization is mobile optimization. Nowadays, most users browse the internet using mobile devices, making responsiveness and loading speed on these devices extremely important. Mobile optimization includes responsive design, which automatically adjusts the site's appearance to the device's screen size, and techniques to reduce loading time, such as image compression and code minimization. This not only improves the user experience but also supports search engine positioning, as page loading speed is one of the factors considered by ranking algorithms.

    Optimization for mobile devices is more demanding than for desktops. Often, even if the site optimization for desktop versions is at a good level, mobile versions can present worse results in analytical tools. This is related to differences in processing and displaying content on smaller screens and the limitations of mobile networks. It's important not to be overly concerned if perfect results are not achieved in every aspect of mobile optimization, as long as the overall user experience is satisfactory and the site is functional. Striving for perfection is desirable, but the technical realities and limitations of mobile devices should be remembered.

    Using CDN and network optimization

    Using Content Delivery Networks (CDN) is another step to optimize application performance. CDN involves distributing site resources, such as CSS, JavaScript files, and images, on servers located around the world. This way, a user loading the page receives content from the server closest to their location, significantly shortening the loading time. Implementing a CDN not only speeds up content access but also reduces the main server's load, which is particularly important with high traffic. Additionally, CDNs can enhance site security, offering protection against DDoS attacks. This happens because CDNs spread traffic across a wide network of servers, allowing the absorption and dispersion of large amounts of network traffic, reducing the risk of overloading a single server. Such a solution not only protects against loss of availability but also ensures the continuity of the service, even in the face of cyber-attack attempts.

    Practical tools and technologies supporting optimization

    The choice of tools for optimizing web applications depends on the project's complexity and budget. For simple applications, a free tool like Google Lighthouse, offering a basic performance audit, may be ideal. WebPageTest, also free, provides a more detailed analysis, useful for moderately advanced projects. For complex applications, GTmetrix (partially paid) offers real-time monitoring and analysis from different locations, which is beneficial for large projects. Each tool has its pros and cons, from ease of use to depth of analysis, which should be considered when matching to project needs.

    Pros and cons of tools:

    • Google Lighthouse: Free, easy to use, ideal for beginners. Offers quick analysis with basic recommendations, but may not cover all optimization scenarios for very complex pages.

    • WebPageTest: More detailed than Lighthouse, allows for tests from different locations and configurations. It's free, but its advanced options may require some technical knowledge.

    • GTmetrix: Offers detailed reports and real-time monitoring, but the best features are paid. Ideal for advanced users and large projects requiring continuous monitoring.

    Comparison of tools in a nutshell:

    • Google Lighthouse

      • Type: Free
      • Cons: Limited advanced analyses
      • Pros: Simplicity, accessibility
      • For applications: Simple to moderately complex
    • WebPageTest

      • Type: Free
      • Cons: Requires some technical knowledge for advanced features
      • Pros: Detailed analysis, tests from various locations
      • For applications: Moderately complex to advanced
    • GTmetrix

      • Type: Partially paid
      • Cons: Cost for full features
      • Pros: Real-time monitoring, comprehensive analysis
      • For applications: Complex, large projects

    Ensuring Security While Enhancing Performance

    According to Terranova Security, 98% of web applications are vulnerable to cyber attacks due to malware and redirection. About 72% are vulnerable due to coding flaws, and 95% of data breaches are due to human error. Therefore, it is essential to take the necessary steps to ensure high security for web applications while simultaneously enhancing performance. Organizations must consider security and performance optimization by practicing the following:

    Encrypt Web App Data

    Though it is one of the oldest data security practices, it is still one of the most widely used ones. Encrypting data means encoding sensitive data and preventing unauthorized access to protect data privacy and ensure safety. Even if someone tries to access the data, they will require user permission and password. To make the implementation more secure, make sure to keep your web app up-to-date with the latest SSL certificate or HTTPS.

    Manage Access Control

    Managing data access limits the accessibility of unauthorized users. It means restricting the data and providing access only to those who will need to work on it. This way, even if someone tries to break into the system, they cannot get any further than the allowed area. However, if you are implementing this in your organization, you must change the access control permission if the designated person leaves the job.

    Use Web Application Firewall (WAF)

    If you want to ensure cyber protection against ever-changing malicious and security attacks, the best thing to do is to use a web application firewall (WAF). It will track and monitor your website traffic in real-time and prevent unauthorized data or information from leaving the application. Generally, WAF protects web applications from threats like file inclusion, cross-site scripting (XSS), cross-site forgery, SQL injection, etc.

    Identify Vulnerability and Carry Out A Threat Assessment

    Audit your entire security system to identify security vulnerabilities and classify them as necessary. It will give you an insight into what to protect and which areas need more priority. Identifying and specifying these vulnerabilities will help you assign security measures accordingly.

    Educate and Train Your Team

    Ensuring web application security is not just the responsibility of the IT department. Educating all the employees, even the management teams, can help prevent attacks or take measures as soon as the system goes under attack without much delay. That is why it is vital to adopt DevOps or Agile methodology in the organization.

    Update and Test Your System Regularly

    The security attack system is always changing and evolving, just like everything else. To fight against it and protect your web application, you must update the tools and system regularly. Failing to do so will only increase the application's vulnerability, and attackers can easily identify these weaknesses. However, as you update your system to the latest version, it fixes the possible weaknesses and bugs, ensures better security, and enables smooth performance.


    In summary, optimizing the performance of web applications is crucial for improving user experience, increasing conversions, and improving search result positions. Using tools such as Google Lighthouse, WebPageTest, or GTmetrix allows for identifying and resolving performance issues, and techniques like caching, image optimization, and choosing between SSR and CSR, contribute to faster page loading. CDN further speeds up content access and enhances security.


    1. Is performance optimization important for SEO? Yes, because page loading speed affects search result positions.

    2. How often should a website's performance audit be conducted? Regular audits are recommended, especially after making major changes to the site.

    3. Is there a universal tool for optimization? There is no one tool perfect for every site; the choice depends on specific needs.

    4. Is mobile optimization more important than desktop? Both are important, but with the increasing number of mobile users, mobile optimization becomes a priority.

    5. Is CDN necessary for every site? Not every site requires CDN, but it can significantly improve performance for sites with international reach.

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