The srsltid URL parameter are added for Merchant Center "auto-tagging" as described by this Google support page. It's only added when a site-owner has activated that feature. They're used for conversion tracking for merchants.
They're added in search directly, with unique IDs using the srsltid URL parameter. Data in RUMvision shows that 5 to sometimes even 17% of pagehits include this new srsltid URL parameter.
srsltid solutions
In general, the following solutions has been proposed by SEO blogs to combat issues with srsltid parameter:
- disable srsltid
Deselecting auto-tagging option in Merchant Center Conversion Settings. Do note this results in losing performance tracking of free listings through Google Merchant Center. - canonical tag
adding canonical metatags to your pages that excludes query strings that could result in duplicate content (if you haven't done this yet)
However, it turns out that this parameter should not have an impact on SEO and crawlability.
This doesn't affect crawling, indexing, or ranking - it's basically just for analytics for merchants
John Mueller on LinkedIn
Impact on Core Web Vitals
RUMvision data is showing that this statement isn't fully true. That's because the srsltid parameter is new to many site owners. Because of this, many site owners and hosting companies haven't added this parameters to their caching strategy.
As a result, caching layers won't recognize this parameter and won't apply their caching mechanisms. This leads to users visiting pages that needs to be fully generated by platforms like Magento and Shopify.
Increased TTFB
This then leads to a higher server response time, which will directly increase the Time to First Byte (TTFB) metric. You might recognize this as we wrote about this before in regards of Google Ads impacting Core Web Vitals.
The following screenshot of a merchant using RUMvision is confirming the impact on the TTFB metric at the 75th percentile:
In this example of a real shop, we can see that the srsltid parameter is 111.8% worse than the overall TTFB. And even more when you would compare 1417ms TTFB with the TTFB of 302ms that could have been achieved with a proper caching strategy.
And when TTFB regresses, the First Contentful Paint (FCP) and Largest Contentful Paint (LCP) will regress as well. The latter (LCP) is part of Core Web Vitals.
Page Experience ranking signal
As Core Web Vitals is part of the Page Experience ranking signal, this new parameter is in fact likely to impact your SEO ranking.
Mitigating the impact on Core Web Vitals
This means you would want to prevent the srsltid URL parameter from impacting your Core Web Vitals. Continuous pagespeed monitoring is the solution here.
Real User Monitoring
Real User Monitoring (RUM) in particular is the solution here, as RUM will expose new conditions you weren't aware of before. This includes new URL parameters like srsltid. Obviously, RUMvision is such a solution that individually tracks the impact for each URL parameter combination.
This will help site owners to compare such list with their caching strategy and properly align their caching rules. TTFB should then restore, improving FCP and LCP metrics at the same time.
Announcement by RUMvision
Users of our RUMvision monitoring solutions have received a detailed mail already to actively inform them, including necessary steps to mitigate the impact.
