Most web agencies and SaaS websites suffer from a silent conversion killer: terrible mobile performance.
It’s surprisingly easy to get a 95+ score on desktop when running Lighthouse on an M3 MacBook over high-speed fiber. But when you switch that toggle to Mobile—where Google simulates an emulated budget Android device throttled to a 1.6 Mbps 4G connection with 150ms round-trip latency—the score crumbles into the 40s–70s.
When we audited the initial release of Klickspell, we hit a familiar plateau: our desktop score was 99, but mobile was lagging with sluggish paint times, render-blocking chains, and cumulative layout shifts.
We didn't want a "good enough" 85. We wanted 98–99 on Mobile and 99 on Desktop with 0 ms Total Blocking Time (TBT) and zero layout shift (CLS: 0).
Here is the exact, step-by-step engineering playbook we followed to get there.
