Most slow and under-performing applications have a common set of issues affecting their performance. These problems often stem from sub-optimal handling of server-side functions, inefficient main thread application operations, and incorrect rendering methods. I tried to cover usual suspects and provide universal strategies that significantly improve your application's performance, therefore elevating the user experience.

Typically, these problems emerge from three core operations: server-side functions, main thread application activities, and interface layout.

• Server-side issues: Frequent HTTP requests and reception of large amounts of extraneous data diminish the server's efficiency. API errors and latency, along with improper data compression, further exacerbate this issue.
• Main thread woes: Heavy duty operations performed on the main thread bog down the application. Inefficient design and execution of database operations worsen the problem.
• Interface Missteps: Incorrectly rendered shadows in the user interface contribute significantly to the slow performance of an app.
  Troublesome as these issues may be, they are surmountable. Let's explore some universal, applicable solutions.

The list provided below includes universally applicable methods to enhance your app's performance and thereby improve user experience.

1. One of the key solutions is efficient data caching. Caching specific files and computational operations on local memory enhances data access speed and keeps the application running smoothly during network interruptions. However, it is equally crucial to strike a balance to avoid serving outdated data or exceeding local storage limits.
2. Large, unoptimized images often decrease loading speed. Making use of image resizing and compression techniques reduces image weight while maintaining quality, resulting in better application load times.
3. The initial impression is crucial. A target launch time of 1.5-2 seconds ensures the application creates a positive first impact. Achieving this involves:
   • Prioritize the rendering of the first screen by postponing any heavy tasks that are not necessary for the app's initialization until after it is rendered.
   • Rather than loading data at the inception of the app, do so when the related screen is opened (e.g., user profile).
   • Implement a gradual data loading process: first display the most critical elements and use placeholders for content of less importance.
   • Utilize splash (loading) screens. Although they do not actually hasten your app load time, they create a perceived faster, responsive app. Even if the app is slower to load, the user is less likely to perceive it as unresponsive. This strategy also upholds brand integrity, and in some instances, produces a wow-effect.
4. Maintaining a clean, lean codebase enhances application performance. This includes keeping an eye on memory leaks, correctly rendering shadows, prioritizing operations, monitoring energy consumption, and creating offline modes. Keeping the code updated and removing unused frameworks are also necessary.
   • Make sure to keep your code fresh by keeping it updated and getting rid of any frameworks not in use. This keeps your app sprightly and ready to launch faster!
   • Be on the lookout for memory leaks! Nip them in the bud as soon as possible because when unwanted objects can't be removed from RAM, your app might get shut down due to memory shortage. A memory profiler can be a handy tool to keep track of object lifecycles and to optimize memory usage.
   • Shadow rendering is key. This calls for keen attention to the shadow's dimensions and features, so they're calculated just once instead of multiple recalculations during screen movement. The techniques vary for each platform, so do your research and find the best practice for your specific platform.
   • We all have our priorities, and so should your operations! Cut down on heavy duty initialization to avoid any bottlenecks. Send blocking tasks packing from the main thread to the background threads for smooth, fuss-free async tasks.
   • Keep tabs on your app's energy use in all stages, whether in operation mode or chilling in the background.
5. Reduce data load times by improving the design of the client-server API. This includes limiting unnecessary data, adapting for slower connections, using content delivery networks, and implementing pagination mechanisms. It's also important to avoid redirects during the application launch.
   • Consider structuring your client-server API such that your user doesn't end up with a tonne of unneeded dat Group your content and objects based on their function and call them up when needed. This technique cuts down on the amount of data that needs loading, allowing your app to load up more quickly!
   • When creating your API, bear in mind that not everyone's running on a snappy 4G connection. There are folks out there still on 3G or even less reliable networks! In such scenarios, try to break down complex requests into smaller, bite-sized ones, and execute them bit by bit. Also, make sure to test your app on slower networks to get the experience right!
   • You should use a CDN or Content Delivery Network to speed up data loading times. This helps by shrinking the distance between the user and the source the data's coming from.
   • For handling bulk data, putting a pagination system in action works wonders! For instance, instead of making someone wait for a hundred news feed items to load at once, show them the first ten. The rest can then load as the user continues to scroll or switch pages.
   • Lastly, try to keep away from redirects while the app's launching. These can add to how long it takes for the data to reach the end-user.

Your application's performance affects the user experience. This points serve as a road map to addressing common performance issues and implementing effective optimizations. Each step you take in this journey could make your application faster, sleeker, and more satisfying to use. As always, remember that application optimization isn't a one-size-fits-all solution. Tailoring these techniques to fit your unique application needs will lead to the best results.