It depends on the traffic and conversion data.
UI and conversion rate optimisation are meant to improve how users experience your website and ultimately increase sales or enquiries. If a particular page is already receiving a significant amount of traffic but converting terribly, fixing its layout, messaging, or call-to-action can have an immediate revenue impact.
At our agency, we prioritise UI/CRO improvements first only when certain pages are getting meaningful traffic — especially paid traffic — and clearly underperforming. In this case, it makes sense to plug the leak before driving even more visitors to the same weak page.
However, UI improvements alone won’t necessarily or directly improve organic search performance, so you also want to address the SEO fundamentals asap. SEO basics — such as indexing, on-page optimisation, and link building — are what help you attract new customers in the first place.
If you’re unsure about the direction, the next step is to ask your agency to clarify the reasoning. Are they fixing a conversion bottleneck, or are SEO fundamentals truly being neglected?
Both SEO and CRO matter. The key is knowing which problem is costing you more right now.