How to Manage Page Speed During a Site Migration
A new platform can make your site faster or slower. Here is why performance can change during a migration, how to protect your Core Web Vitals, and how to handle mobile considerations during the move.
Page speed can change during a migration because a new platform, theme, hosting or code can perform differently, so a site can end up faster or slower. Protect it by benchmarking current speed, testing the new site on staging, optimising images, code and caching before launch, and comparing after go-live. Core Web Vitals (loading, interactivity, visual stability) can shift on a new build, so test them before and after. Because Google uses mobile-first indexing, make sure the new site is fully mobile-friendly, content matches desktop, and mobile speed is tested. Then compare against benchmarks and fix regressions.
Why speed can change, and how to protect it
Page speed can change during a migration because a new platform, theme, hosting or code can perform differently from the old one, so a site can end up faster or slower, and since speed affects both experience and SEO it needs checking. A move is a chance to improve speed, but also a risk of regressing it; because performance can shift either way, measuring and managing page speed is an important part of a migration. You protect page speed during a migration by benchmarking current speed before the move, testing the new site's performance on staging, optimising images, code and caching before launch, and comparing speed after go-live so any regression is caught and fixed. Testing on staging means slow pages are found before they are public, which ties into the benchmarks from your pre-migration audit; because speed is easier to protect before launch than to rescue after, measuring and optimising throughout the migration is the reliable approach.
Benchmark first
Know your current speed.
Core Web Vitals
Test loading and stability.
Mobile-first
Test the mobile version fully.
Core Web Vitals, mobile considerations, and checking after launch
Core Web Vitals are Google's measures of loading, interactivity and visual stability, and they matter during a migration because a new build can change them, so you should check them on the new site and address any that regress. They are part of how Google assesses page experience; because a migration can affect these metrics, testing Core Web Vitals before and after the move helps protect performance. The mobile considerations that matter during a migration are that, because Google predominantly uses mobile-first indexing, you must make sure the new site is fully mobile-friendly, that mobile content matches desktop, and that mobile speed and usability are tested, so the migration does not harm how the site performs for mobile users and in search. Mobile is how most people and Google see the site; because mobile-first indexing makes the mobile version central, thorough mobile testing is essential in any migration. You check performance after launch by testing page speed and Core Web Vitals on key pages after go-live, comparing them against your pre-migration benchmarks, monitoring real-user data in Search Console, and fixing any pages that regressed. Comparing to benchmarks turns vague impressions into clear evidence, feeding into your wider post-migration monitoring. Because performance issues can appear once the site is live and under real traffic, monitoring and fixing after launch is part of managing speed through a migration.
A faster site, not a slower one.
On every device.
A migration can quietly slow your site down if performance is not watched. We benchmark your speed, test the new build and its Core Web Vitals on staging, check the mobile version thoroughly, and compare after launch, so the move protects performance rather than costing it.
Everything included in your plan:
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