Why can redirects be slow?

Redirects can result in latency because the client needs to make an additional request to the new URL specified in the response headers. This adds an extra round trip time (RTT) as compared to directly accessing the desired resource.

Additionally, if there are multiple redirects in place, each redirection adds further delays as each subsequent request has to be processed.

Several factors contribute to redirect latency

When a redirect is triggered, whether it's due to a change in URL structure, domain migration, or simply forwarding users from an old page to a new one, there is typically some additional processing time involved before reaching the final destination. This can impact website performance and user experience.

• Server processing: When a request for redirection is received by the server, it needs to process this information and determine where to send the user next. The server may perform several operations before issuing the redirect instruction.
• DNS lookups: If the redirected URL involves switching domains (cross-origin redirects), resolving DNS (Domain Name System) queries might introduce additional delays as servers look up IP addresses associated with specific domain names, establishing TCP connections and TLS (SSL) handshakes. If any of these steps encounter delays or issues, it prolongs the overall time taken for serving content to users.
• Network latency: The physical distance between client devices and servers introduces network latency as data travels across various routers and switches. Redirects involving cross-continental transfers may experience higher latency compared to those within local networks.
• HTTP request/response cycle: Each redirected request adds extra steps in the HTTP cycle – initial request processing, response generation by server-side scripts/frameworks, transmission of response headers back to clients – leading to increased overall loading times.
• Caching: Web browsers often cache redirects temporarily so that subsequent requests do not require contacting the original server again immediately after redirection has occurred; however, this caching behavior can cause issues when updates are made but are not recognized until cached redirects expire.

Minimize redirect latency

To minimize redirect latency, website owners can optimize their server configurations, reduce unnecessary redirects, use caching techniques, and ensure efficient code execution during redirection processes.

There are several ways to minimize redirect latency and optimize website performance:

• Use direct links: Instead of using short URLs, redirecting services, client-side or server-side redirects, use direct links to the desired webpage. Make sure all links point directly to the intended destination. If a redirect is no longer needed or serves no purpose, remove it from your website's configuration. This eliminates the need for additional redirects.
• Minimize chained redirects: Avoid having multiple sequential redirects in your website's architecture as each redirect adds extra latency overhead. Analyze your site's structure and eliminate unnecessary intermediaries if possible.
• Utilize cache mechanisms: Implement caching mechanisms to store and deliver redirects, so that subsequent requests can be served directly from cache without invoking any additional lookups or processing, reducing the need for repeated server-side processing.
• Optimize server response time: Ensure efficient hardware configurations and optimized software settings for faster processing of redirect requests. Improve the performance of your web server by optimizing code and server configurations like compression and caching headers to ensure quick responses when performing a redirect.
• Localize servers: Place servers closer to user locations or utilize content delivery networks (CDNs) for reduced network latency.
• Avoid cross-origin redirects: You not only want to minimise redirects by reducing the number of same-origin redirects (redirects that occur within the same domain or origin). You should also aim to keep redirects within the same origin whenever possible. This means ensuring that all your necessary redirections occur within your own domain. By doing so, you eliminate the need for additional DNS lookups, TCP connections and TLS (SSL) handshakes, and minimize any latency introduced by cross-origin redirects. A cross-origin redirect happens when a web page on one origin redirects to a URL belonging to a different origin. For example, if a user visits "www.example.com" and gets redirected to "www.anotherdomain.com", it is considered a cross-origin redirect.
• Offloading redirects to the server-level: Offloading redirects to the server-level means that the task of handling redirects is handled by the web server itself, rather than at the application-level or CMS-level. Handling redirects at the server level reduces overhead on the application or CMS, allowing them to focus on serving content and processing requests more efficiently. Server-level redirects are typically faster as they bypass any additional processing required by applications or CMS platforms. Managing redirects directly at the server level offers a centralized approach, making it easier to configure and maintain redirection rules across multiple websites or applications hosted on that server. By moving redirect management away from applications or CMS platforms, there is less chance for misconfigurations or mistakes that could lead to incorrect redirections.
• Offloading redirects to the edge: Instead of handling the redirects on the server-side, they are handled by a content delivery network (CDN), preferably edge servers close to the user. On average, latency redirects at a CDN may add anywhere from 10 milliseconds to a few hundred milliseconds of extra delay. However, CDNs are designed to optimize this process and minimize redirect times as much as possible.
• Use the X-Redirect-By header: The X-Redirect-By header is a non-standard HTTP response header that can be used to indicate the method or technology by which a redirect was performed. It primarily helps in debugging and understanding the redirection process. By using this header, it is easy to indicate the system that set the redirect, which helps to optimise, remove or update redirects.
• Use the HSTS header: The HTTP Strict Transport Security (HSTS) header is used to improve the security of web applications by enforcing secure connections over HTTPS. By utilizing HSTS, websites can provide a more seamless experience for users, it instructs the browser to always load the webpage over HTTPS, even if the user types "http://" in the address bar or clicks on an insecure link. This eliminates additional latency when redirecting the user from HTTP to HTTPS. When a browser receives an HSTS header from a website, it remembers this information and automatically loads the webpage over HTTPS in subsequent visits. However, this behavior does not apply to the first visit to that particular website. To enable HSTS for the initial visit as well, you can add your domain to the preload list used by browsers.

Are there thresholds for slow redirects?

In general, lower latency is preferred for a better user experience and faster website loading times.

When measuring redirect latency, each individual redirect in a sequence is measured separately. This means that if there are multiple redirects involved in getting from the initial URL to the final destination URL, each redirect will have its own latency measurement.

According to httpstatus.io, the following redirect latency thresholds for a single redirect can be used as a general guideline:

• Good: Below 100ms - Redirect latency below 100ms is considered good and indicates a fast redirection process with minimal delay in the redirection process.
• Moderate: Between 100ms and 300ms - While not ideal, this range is still considered acceptable for most cases. However, there may be a noticeable delay in the redirection process.
• Poor: Above 300ms - Redirect latencies exceeding this threshold are generally considered poor and can significantly impact user experience. Users may experience frustrating delays before being redirected to their desired destination.

Keep in mind that these thresholds are not set in stone and can vary depending on the specific context or industry standards. Additionally, it's important to consider other factors such as network speed and device capabilities when evaluating redirect latency.

Overall, while redirects are sometimes necessary for various reasons like website restructuring or handling outdated URLs, they introduce extra steps that can slow down page load times and impact user experience. Minimizing redirect latency is crucial in providing a seamless user experience by reducing unnecessary waiting times during navigation between web pages or URLs.