Build for a phone with one bar on the platform at Atlantic Avenue
Your visitors are in transit far more often than they are at a desk, and the connection they have is worse than anything your team tests on.
Brokers open listings between tours. Tenants open them on the way to one. Signal cuts out between stops, comes back at the platform and cuts again. A page that needs three seconds of JavaScript before it renders an address is a page nobody read.
Text first. The address, the floor, the square footage and a phone number should be in the initial HTML, not assembled after a script decides what to show. Images load after, sized for a phone, not straight off a photographer's export.
Set a weight budget and enforce it. Hero video and full resolution floor plans are the usual culprits, and the map is often the single heaviest thing on the page. A static map image that loads instantly and swaps to an interactive one on tap costs nothing and saves the visit.
Test on a throttled connection rather than office fiber. A site that feels fast in your conference room and stalls on the Q train is failing in the only conditions that matter.