Say it straight or don't say it at all.
If a local business website feels slow on mobile, it is probably costing leads. Speed is not a technical vanity metric. It affects trust and action.
Most business owners have no idea whether their website is generating anything. They think it is fine because it exists. That is not a metric. Here is how to actually find out.
PNG files are massive compared to modern formats. A WebP image can be 12 to 14 times smaller at the same visual quality. If your site still uses PNGs, you are paying for that in load time and rankings.
A slow website costs you in two ways simultaneously: lower search rankings and worse conversion rates. Both of those hit revenue. Speed is not a technical nice-to-have. It is a business issue.