Stefan Trajkov™

Web Performance: The Problems

We’ve learnt already in the first part of this web performance series why performance is important and should be budgeted for at every stage of product development, what benefits it holds for businesses and products, and the negatives of poor performance. Now, let’s talk about the problems of web performance; what makes sites slow.

What makes sites slow?

No doubt, there’s a ton of reasons why websites are slow, some of which are case-specific. I like to look at these factors from two perspectives:

  • the user perspective
  • the developer perspective

Really, the user and the developer are the two main parties involved in this discussion; all other factors that impact web performance like the network from which the site is accessed, the hardware specs of the device, and the software fall under the user factor. Same way, developers are responsible for whatever impacts performance on the tech part of it. So, basically, these two guys are the players in this game.

That being said, in this article, we’ll look at things less from user perspective, and focus on the development side because most of the problems come from there, and to move forward, developers have to build with the users in mind and the various real-life situations they could be caught up in because we definitely can’t control them; we can’t move all our users to a luxury place with super-fast internet connection and great devices — that’s unrealistic. So, let’s jump right into what makes sites on the internet slow today.

Apart from network, hardware, and software limitations which are user factors, let’s actually talk about the technical causes of poor performance on the front end.

1. Third-party resources and scripts

It’s an absolutely normal and almost inevitable practice to have third-party resources and scripts on our sites because we most of the time consume third-party content and services whether it’s analytics, ads, social media plugins, framework/library resources, we use them.

However, so many times, the authors of these third-party resources just tell us to plug in their resources to our sites: resources that might depend on other resources all the way down or might be poorly developed, and then they serve us. The fact, however, remains that most of these assets are the leading cause of performance problems on the web because of course, we didn’t build them, we don’t know how they were built, we do not own them, all we want is their services and we can’t determine the quality of these services, we can only assess them and act based on the information.

It’s sad news that third-party resources today have taken over control of tons of sites that they start to have unintended (sometimes malicious) side effects, and as developers, most of the time we’re just lazy to take it back. It’s very common to see sites include a huge third-party resource, and then end up using a very minimal portion of it, say 5% e.g including a 20kb library only to end up using a component that’s barely worth a kilobyte. That’s usually not a great idea as most of these things can easily be implemented in-house with just a little bit extra work.

2. Heavy assets and resources

We all have that one big file on our sites – the one big JavaScript asset or the pretty 1MB image from Unsplash. JavaScript is on top of the list of frontend resources that impact performance negatively, followed by images and really, it’s difficult to keep track of these things when everyone is in a rush and hell-bent on results so we under-prioritize or forget about optmizing for performance, something that affects our users directly. Users know when your site is slow, they also know most times what sites consume a lot of their mobile data.

Engineers write code and craft experiences they find pleasing which more often than not is at the expense of the user — forgetting what the user needs and what they perceive to be a great experience. The user has no idea how fancy your code is or what shiny new tech you’re using, they just want to be able to use your product and have a great experience doing that. And so, if your site is not accessible quickly, you do not even get the chance to show anything to the user.

3. Excessive HTTP Requests

Get! Post! Frontend developers, we love to do that a lot: consuming APIs and all — it’s fun actually, being able to communicate with a web server, that’s pretty incredible, right?

Well, yes, it is but sure comes at a cost. Sending requests back and forth can quickly become overwhelming for a web server to handle. Imagine for a moment that you’re going to get a snack one day at the office and then, a superior calls and says “hey, on your way, please get me some venti iced skinny hazelnut macchiato, sugar-free syrup, extra shot, light ice, no whip coffee”. Extremely confusing, yeah?

Similar can happen with your server when making requests. If you observe from that order, the entire purpose and what matters to you the most is getting your snack, just the way your users want to use your product — they want to satisfy themselves. Too bad their superior (engineers in this case) took that privilege away from them. You know how tough it can be to say no to that – same way the server can’t say no to your multiple requests. It just must (or at least attempt to) process the requests regardless of how complicated it is.

Your user might not need all the junks and stuff you’re fetching for them on the initial load, they need what matters, and you’re in place to answer those questions. Identify the things you’d want to have on your screen quickly if you were the user.

4. Poor Code Quality

Everyone likes to hop on their computer to start writing code which often gets us distracted to the point we forget to ask ourselves essential questions like “Am I doing it the right way?”, “Can this be done better?”, “What are the implications of doing it this way?”.

A lot from the code quality can affect the performance of your site or product as an entity. Whether you’re implementing a functionality that should take 10 lines of code in 50 lines, there’s so much dead code, or you’re just writing the code or using a tool in a way that it’s much slower to function; they all impact performance. For example, having excessive unused code bumps up file sizes which could delay HTTP requests and in turn, affect performance.

In fact, all the points listed previously in one way or the other fall under the quality of code you’re delivering and how knowledgeable a developer might be with regards to performance. Your JavaScript, CSS, HTML and other applications on the backend contribute to performance directly or indirectly.

There are some industry standards and practices that should be followed while building sites. Don’t write code that “just works™”. You should consider if you’re actually solving that problem in the most efficient way.

5. Inadequate server resources

One critical factor often overlooked is the capabilities of the web server behind a frontend. Nearly all articles and discussions about performance are usually focused on the frontend. Now, while that isn’t wrong as most of the work is usually on the frontend, the server that powers a frontend can also greatly affect overall performance.

I mean, sure, you could have a pretty fast frontend but if your server fails to respond on time, the frontend never even makes it. So, what do I mean? Some servers have very high TTFB (Time to First Byte) which is the time it takes for the client get the first byte of response data from a server after an HTTP request, and so if that server’s hardware (CPU, RAM etc) is inferior or insufficient and it takes long (more than 600ms on an average network) to get a response for just the main document request, that’s a prolonged page load and so your user just stares at a blank screen for seconds with no sign of progress which can be really frustrating. Now, even when we get a response for that main document request, subsequent resources like scripts, css and images (all of which point to the server) still have to get their first byte of response data and fully download which can really slow things down.


Now that you have a clearer view on why performance matters and the several factors that influence performance, including a few instances of not-so-good practices, in the final part of this series, we’ll talk about known and tested strategies to tackle these problems.

In summary, how we build what we build matters because that’s a huge part of the product no matter what it’s later transformed to. That’s what we serve users, and so priority should be given to what matters to the user, and not how quickly we can achieve something that might not be the best experience for users.