Server-Side vs. Client-Side Caching: What is Best for Your Website?

June 5, 2024

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If you want your website to load in a flash, implementing a proper caching strategy is a great place to start. 

Caching is the process of storing your website’s data in a cache, a storage location, to provide quicker access to your users. This process is crucial for improving site performance and overall user experience, whether on the server or in the browser. The tricky part is understanding these caching techniques and deciding which one will serve your eCommerce store best. 

So, do you know which caching technique is right for you? Let's explore what caching is, how it works, and the differences between server-side and client-side caching.

Caching in Simple Terms

Say you’re on a long hike through a world-renowned nature park. The sun is out, and while the scenery is beautiful, you are going through your water much faster than you anticipated. Luckily, there is a place to refill your bottle halfway through, but it still takes you an hour to get there… and then another hour to get back.

Now, imagine park rangers have set up water stations at regular intervals throughout the area. Instead of waiting an hour to get more water, you can access this crucial resource every 15 minutes.

In this example, the water is your website’s data, which you want your customers to have as soon as possible for a great user experience.

Software engineers, also known as metaphorical park rangers, have created caching systems to provide efficient resource delivery, but on a much faster scale.

Now that we have a general, simplified understanding of caching, let's delve deeper into the technical side of it.

Caching in Technical Terms 

When a user first visits your homepage, they make a request to get all the files that make up that page. If that customer lives in Mexico, but your website is hosted by an origin server in Japan, your data would have to travel more than 6,000 miles to reach them. 

Even with today’s technology, that could take several seconds too long, considering latency—how long it takes for data to travel from its origin to its destination—is the number one reason shoppers abandon carts.

That’s where caching comes in. Copies of your site’s data can be cached—or temporarily stored—in CDN servers located much closer to your customer’s location. A cache provides a special memory area where temporary files or data from apps, servers, websites, or browsers get stored. Helping your content load faster when a user requests it. 

Caching is everywhere in technology, from the devices you use to the websites you visit. A typical website receives numerous visits daily, requiring the server to display the page from scratch for each user. This involves a complex process of DNS lookup, HTTP requests, and data packet transfers, which can be time-consuming.

Caching mitigates this by storing a copy of the web page’s content temporarily, enabling faster load times for repeat visits without making new requests to the server. The benefits of caching include:

  • Reduced latency
  • Clear increases in speed
  • Load reductions for your host server
  • A much better user experience

Why Caching is Important in eCommerce

Website caching is essential for delivering excellent performance and a smooth user experience for your eCommerce store. Beyond enhancing performance, effective caching influences several key aspects of your store's success. Whether it's Google recognizing it or your everyday visitors, a speedy site brings you the following benefits:

  • Increased conversion rate - Research shows that eCommerce sites loading in one second or faster have double the conversion rate compared to those that load in two seconds. If your site takes three seconds to load, only 1.12% of visitors will convert, with this rate dropping by half if the load time reaches four seconds. 
  • Boosted SEO ranking- Faster sites hold higher performance scores indicating to Google that your website is user friendly. Google recognizes this and in return rewards your site with a higher ranking in the search results. 
  • Increased Average Order Value- The longer a user stays on your site, the higher the probability they will add more items to their cart. According to a study by Deloitte, a mere 0.1-second improvement in site speed led to a 9.2% increase in average order value.
  • Decreased Bounce Rate- It’s no surprise that the faster your site loads, the less likely users are to  get frustrated and leave. In fact, a study by Google found that 53% of mobile website visitors will leave a webpage that doesn’t load within three seconds.
  • Reduced Ad Spend- Faster site speeds contribute to better Quality Scores in Google Ads, which can lower your cost-per-click (CPC) and enhance the performance of your advertising campaigns. A great example is when Nood onboarded with us at Nostra. By reducing latency and boosting their site performance, we achieved a 25% decrease in their cost per add-to-cart.

If you're looking to achieve these advantages, utilizing a caching system is a great way to get there. Let’s review the main caching strategies that are particularly relevant in the world of eCommerce. These caching strategies are designed to enhance different stages of the shopping experience:

  • Product Page Caching

This involves specifically storing fully rendered product detail pages. This improves load times, ensuring customers can quickly view items (and add more items to their cart), and reduces server load by serving cached pages instead of regenerating them from scratch.

  • Cart Caching

This involves storing the contents and state of a user's shopping cart. In doing this you can speed up the shopping cart experience, allowing users to add, remove, and view items with minimal delay, enhancing overall user satisfaction.

  • Dynamic Pricing Caching

This type of caching stores pre-calculated pricing information. This ensures that users see up-to-date prices quickly without slowing down the browsing experience, optimizing the performance of pricing calculations.

  • Hybrid Caching 

While this type of caching is a combination of both server-side and client-side caching, it is one of the most frequently used caching techniques for achieving optimal performance. This is made possible by using both server-side caching to reduce the load on your server and speed up data retrieval, while also using client-side caching to store data in the user's browser for quick access without repeated server requests. This approach offers the best of both worlds, ensuring faster load times, reduced server strain, and an enhanced user experience. It is a common practice for modern websites aiming to deliver high performance and reliability.

Caching comes in various forms and uses, each enhancing user experience by providing that extra touch of speed and efficiency. Let’s now get to the main event, server-side caching and client-side caching. 

Server-Side Caching and its Benefits

What is server-side caching? It all begins when the first user requests a web page. The website undergoes the normal process of retrieving data from the origin server and constructing the webpage. After the request has been processed and the response has been sent back, the caching server (acting as the intermediary) copies the webpage and stores it as a cache. 

This is where the beauty of server-side caching comes into play, for when that user or any other user afterwards requests that same webpage, it is instantly loaded. This is because the website has been cached and a copy is now stored on the caching server. This method makes the entire process faster, reaping the following benefits:

Increased Performance: Server-side caching can significantly speed up response times by reducing the time needed to retrieve data or perform calculations. When the server stores frequently accessed data in the cache, it can serve requests almost instantly without querying the database or processing the data again. This leads to faster page loads and improved user experience.

Reduced Server Load: With cached data readily available, the server experiences less strain, as it doesn't need to handle as many database queries or execute complex operations repeatedly. This reduction in server load can lead to lower operational costs, as the server hardware and infrastructure can handle more requests with the same resources.

Scalability: Server-side caching enables a website to handle higher volumes of traffic without performance degradation. By efficiently managing cached data, a website can serve more users simultaneously, making it more scalable and resilient to traffic spikes.

Server-side Caching Limitations

As great as server-side caching is, nothing is ever perfect. Let’s discuss the several limitations that come with using this caching strategy:

Data Staleness- Cached data can become outdated, leading to clients receiving old information. To mitigate this, websites must consistently update their data through constant caching whenever changes occur, ensuring that the cache remains fresh and accurate.

Cache Invalidation- This goes hand in hand with data staleness. Cache invalidation is the process of removing or updating cached data that has become outdated to ensure consistency with the underlying data source. Developing and maintaining effective invalidation strategies, such as time-based expiration, event-based updates, manual invalidation, or dependency tracking, can be complex and may reduce the overall benefits of caching if not done properly.

Distributed Systems- Synchronizing caches across multiple nodes in a distributed system can be challenging. Managing network latency and ensuring that all nodes have consistent cached data requires sophisticated coordination and can introduce additional complexity.

Security Risks- Caching sensitive data poses significant security threats, including unauthorized access and cache poisoning. Proper security measures must be in place to protect cached data and prevent malicious attacks that could compromise the integrity of the cache.

Dependency on Cache- The cache layer can become a critical point of failure or a bottleneck in the system. If the cache fails or becomes overloaded, it can severely impact overall system performance, making it essential to have robust cache management and failover mechanisms in place.

Understanding these challenges helps in creating effective caching strategies that optimize performance and mitigate risks. 

The Three Different Types of Server-Side Caching

There are several types of server-side caching, but to save us some time let’s go over the main three techniques out there and how they work. 

Object Caching

Object caching stores the results of database queries to make future data requests faster and reduce the load on the database. To put it in simple terms, Imagine you ask a librarian for a specific book. The librarian finds it and makes a note of where it is. The next time someone asks for the same book, the librarian can quickly get it from the noted location instead of searching for it all over again. 

How is this possible? Let’s get over the basic technical steps. 

How It Works:

  1. When a user requests data that requires a database query (a request to a database to retrieve, insert, update, or delete data, typically written in a specialized language like SQL), the server retrieves the data and stores (or caches) the result.
  2. The next time a user requests the same data, the server can quickly retrieve the cached result instead of querying the database again.

Opcode Caching

Opcode caching is a performance booster for PHP applications that involves storing the compiled bytecode of PHP scripts (a set of instructions written in the PHP programming language that is executed on a web server to generate dynamic web content). To put this in simpler terms, think of it like baking cookies. Normally, you mix the ingredients and bake the cookies every time. Opcode caching is like having pre-mixed cookie dough ready, so you just bake it without having to mix the ingredients again, saving time and effort.

How It Works:

  1. PHP scripts are normally written in human-readable code, which the server needs to compile into machine-readable code (bytecode) each time they are executed.
  2. With opcode caching, the server stores this compiled bytecode so it doesn't need to recompile the same PHP scripts repeatedly.

Content Delivery Network (CDN) Caching

Last but not least is CDN caching. This involves storing copies of web content on multiple servers distributed across various geographical locations. This can be imagined as if your favorite book is stored in libraries all around the world. When you want to read it, you go to the nearest library instead of traveling to the original library, making it faster and more convenient to access. Let’s review how this works in technical terms.

How It Works:

  1. When a user requests a web page, the CDN serves the cached content from the nearest server to the user's location, reducing latency.
  2. The CDN periodically updates its cached content to ensure users receive the latest version without overloading the origin server.

CDN caching is a popular method amongst eCommerce platforms, such platforms tend to use modern content delivery networks (CDNs), such as Cloudflare, to cache static assets. However, CDNs do have some limitations.

Not only do traditional CDNs focus on storing basic static content—the parts of your website that stay the same for every user—but their performance capabilities are limited to their networked locations.

 In contrast, Nostra’s strategy revolves around enabling smart caching mechanisms for static and dynamic content. Our hybrid server-side rendering product utilizes more than 310 edge locations, which are strategically located within 50 milliseconds of 97% of the world’s population.

With serverless functions operating on our edge servers, our software makes decisions before your pages load, ensuring content is delivered to your users faster—and typically improving measured page load times by 20-30%.

Client-Side Caching and its Benefits 

Moving from Server-side caching to Client-side caching. The process of Client-side caching is when stores data on the user's device, typically within their browser. This includes elements like images, stylesheets, and scripts, which are stored temporarily and reused during subsequent visits to the website. Let’s review the benefits of client-side caching as well as the negatives: 

Faster Load Times

Since data is stored locally on the user's device, the browser can load it quickly without making multiple network requests. This results in faster load times for frequently visited websites, as the browser retrieves the cached resources instead of downloading them anew.

Reduced Bandwidth Usage

Fetching data from the local cache instead of the server reduces the amount of data transferred. This can be particularly beneficial for users with limited bandwidth, as it minimizes the need for repeated downloads of the same resources. It also reduces the load on the server's bandwidth, contributing to overall network efficiency.

Enhanced User Experience

Client-side caching improves the overall user experience by making repeated visits to the site faster and smoother. Everyone enjoys quicker page loads and a more responsive site, which in turn increases user satisfaction and the likelihood of users returning to your site.

Client-side Caching Challenges

Client-side caching sounds just as great as server-side, but does have limitations, lets review: 

Storage Limitation: Browsers impose limits on the amount of data that can be stored, which can be insufficient for large or complex applications. Making it not so ideal for big eCommerce sites with tons of products. 

Cache Expiry: Managing cache expiration is challenging, as developers must ensure that the cached data is refreshed appropriately to avoid serving outdated content.

Inconsistent Performance: Client-side caching effectiveness can vary based on the user's device and browser, leading to inconsistent performance across different environments. This especially true when a user switches to a different device, for they will be required to re-downloading the data. 

Limited Control: Developers have limited control over the cache once it's stored on the client side, making it harder to manage and update cached data compared to server-side caching.

There you have it, a deep understanding of caching, server-side caching, and client-side caching. But, before you go let's discuss some key tips in successful caching.

Tips to Keep in Mind Before Starting Your Caching Journey 

Before jumping into caching and investing time and resources. Take into consideration the following tips for they help you along your journey: 

Measuring Caching Effectiveness

If you're going to invest in caching, you want to be able to measure the impact it has on website performance. The key metrics to look out for would be Page Load Times,  Time to First Byte (TTFB), and Cache Hit Ratio.

 These metrics can be found using  tools such as Google's PageSpeed Insights, GTmetrix, or Lighthouse, be sure to monitor them regularly. Failing to do so can lead to undetected issues and poor caching configurations.

Avoid these Common Caching Mistakes 

Over-Caching- Caching too much data or caching data for too long can lead to stale data being served to users, causing outdated information and potential consistency issues.To avoid this issue, implement appropriate cache expiration policies and use cache invalidation strategies to ensure data freshness. 

Under-Caching- Under-caching occurs when a website is not caching enough data or not caching at all. This can lead to negative results in your site’s performance To avoid this mistake,  Identify frequently accessed and computationally expensive data to cache. Use tools to analyze access patterns and adjust caching strategies to maximize performance gains.

Inconsistent Invalidation: This goes back to cache invalidation, failing to properly invalidate or update cached data can lead to serving outdated information to users.That is why it is so important to develop and maintain effective cache invalidation strategies, such as time-based expiration, event-based updates, manual invalidation, or dependency tracking, to ensure cache consistency.

Security Oversights

The last and final tip is to always prioritize your store’s security. Caching involves the distribution of sensitive data, and without proper security measures, it can be exposed to unauthorized access and cache poisoning attacks.

To prevent any security threats, try to implement practices such as encryption and access controls to protect cached data. Additionally, avoid caching highly sensitive information to the best of your ability.

By avoiding these common caching mistakes and striking the right balance, you can maximize the benefits of caching, ensuring  great site performance and a happy user experience. By understanding and implementing these caching strategies effectively, you and your team can create a faster, more efficient, and scalable web experience for your visitors. If you're looking to implement a caching strategy into your eCommerce store, consider Nostra for the job. 

Our hybrid server-side rendering product, the Edge Delivery Engine, exceeds the expectations of any caching technique out there. Through high-speed infrastructure and intelligent page speed optimizations, we can elevate your website’s performance metrics, giving you the fastest website speed while also positively impacting your SEO algorithm rankings. To learn more about us and how we can improve your online store, book a demo today.

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