Sylius and web performance - Olivier Allain & Hélèna Gravelier

Summary

This session focuses on web performance optimization, particularly in e-commerce. Key topics include measuring performance through Core Web Vitals (LCP, FID, CLS), improving server response times with tools like Varnish, and caching strategies to reduce load times. It emphasizes the importance of quick, high-impact improvements, such as implementing effective caching and optimizing server configurations. Additionally, it covers techniques for handling dynamic content and ensuring a seamless user experience even under heavy traffic. The session also discusses tools and practices for tracking and monitoring performance to prevent regressions and improve overall site speed.

Takeaways

• 😀 Web performance is critical for user experience (UX) and has a direct impact on conversions, especially in e-commerce. A slow website can drive users away.
• 😀 Core Web Vitals, such as LCP (Largest Contentful Paint), FID (First Input Delay), and CLS (Cumulative Layout Shift), are key metrics to measure web performance and UX quality.
• 😀 TTFB (Time to First Byte) measures the time it takes for the server to respond to a user request, and optimizing it is crucial for better performance.
• 😀 Caching is essential to improve website speed. Using tools like Varnish and Symphony caching systems can drastically reduce server load and speed up page rendering.
• 😀 Varnish provides extremely fast response times, reducing backend load and improving performance during peak traffic, like during sales or DoS attacks.
• 😀 Properly configured server infrastructure is important, but tools like caching and CDNs can enhance performance, even on less powerful servers.
• 😀 Cache invalidation and warming are essential practices. You need to ensure outdated data is cleared from the cache and that all pages are pre-loaded for faster access.
• 😀 ESI (Edge Side Includes) allows for caching dynamic content selectively, such as personalized prices or user-specific information, while serving static content from the cache.
• 😀 Be mindful of cookies in cache management. Cookies can bypass caches and cause performance issues, so they need to be handled carefully, often by removing unnecessary cookies.
• 😀 Server configurations and performance optimizations are not a replacement for proper hardware. Better server specs (CPU, RAM) combined with caching tools will provide optimal performance.
• 😀 Tools like GTMetrix, PageSpeed Insights, and Coolia's Web Performance Score can help track and measure performance, providing insights into where optimizations are needed.

Q & A

What is web performance, and why is it important?

Web performance refers to the speed at which web pages are downloaded and displayed in a user's browser. It's crucial because slow websites lead to poor user experiences, increased bounce rates, and ultimately lower conversion rates and sales, especially in e-commerce.

How does web performance impact e-commerce websites specifically?

In e-commerce, a fast website enhances user satisfaction, which leads to higher chances of visitors completing purchases. Slow load times can cause users to abandon their shopping carts, resulting in lost revenue.

What are the Core Web Vitals, and why are they important?

Core Web Vitals are a set of metrics introduced by Google that focus on the user experience of a website, including loading performance (LCP), interactivity (FID), and visual stability (CLS). These metrics help determine the overall quality of user experience on a website.

What are some other important performance metrics besides Core Web Vitals?

Other key performance metrics include First Contentful Paint (FCP), which measures the time from when the page starts loading to when the first piece of content is visible, and Time to First Byte (TTFB), which measures the time it takes for the server to respond to a request.

What is TTFB, and how does it affect web performance?

TTFB (Time to First Byte) is the time between when a browser sends a request to a server and when the first byte of data is received from that server. High TTFB can delay page loading, negatively affecting the user experience, especially if the server is underpowered or poorly configured.

How does server configuration impact web performance?

A well-configured server, with adequate CPU, RAM, and optimized settings, ensures faster responses to user requests. A poorly configured server can lead to slow TTFB and overall web performance, even with optimizations like caching.

What is Varnish, and how does it improve web performance?

Varnish is a caching HTTP reverse proxy that helps speed up website performance by caching content closer to the user. It reduces the load on backend servers, delivering pages faster and handling high traffic volumes more efficiently, especially in e-commerce environments.

What are the benefits of using Varnish for caching?

Varnish offers fast response times (around 13 milliseconds), reduces backend server load, supports high traffic peaks, and helps optimize resource usage in cloud environments like AWS or Google Cloud. It also includes a 'grace mode' to serve cached pages while the backend updates.

What challenges might arise when using Varnish for caching?

Varnish does not support SSL in its free version, and measuring performance with Varnish can be challenging. It also requires managing cache invalidation and flushing, and it bypasses the cache when requests contain certain cookies, which may impact dynamic content handling.

How can caching be optimized for e-commerce sites with user-specific data?

For e-commerce sites, caching strategies can be enhanced by using Varnish's Edge Side Includes (ESI) for handling dynamic content like user-specific carts or promotions. Additionally, managing cookies effectively and using different cache layers (like HTTP reverse proxy) can help balance performance and personalization.

What is cache warm-up, and why is it important?

Cache warm-up involves pre-loading the cache with frequently accessed content after updates or new deployments to ensure fast access for users. It helps avoid slow load times for users accessing pages that are not yet cached.

What are some best practices for web performance optimization?

Start with high-impact, quick-to-implement optimizations like caching and reducing external requests. Monitor performance using tools like Google PageSpeed Insights, and avoid unnecessary plugins or features that could add unwanted load. Gradually tackle more complex optimizations after addressing the basics.