Serving large data sets at acceptable latency typically requires some proportional amount of RAM to keep frequently accessed files and indexes in memory (especially if you're serving off of HDDs).
It depends on the service, but we frequently find geo services are RAM limited up to a certain point (at which point there's enough cached to make it CPU limited).
If it's just local--depending on the exact service--you probably wouldn't need a lot of RAM. Expect memory requirements to scale somewhat sub-linearly with diversity of regions simultaneously accessed.
It depends on the service, but we frequently find geo services are RAM limited up to a certain point (at which point there's enough cached to make it CPU limited).