In general, we want to convert strings to StatName during initialization, xDS reload, etc, rather than doing string lookups in the hot-path.

However in some cases this may be unavoidable. For example, stat names can be controlled via HTTP request headers:

https://www.envoyproxy.io/docs/envoy/latest/configuration/http_filters/router_filter#x-envoy-upstream-alt-stat-name

and

https://www.envoyproxy.io/docs/envoy/latest/configuration/http_filters/router_filter#config-http-filters-router-x-envoy-upstream-alt-stat-name

Some sort of stat lookup table can be integrated into Stats::ThreadLocalStore, but should be used sparingly as it will cost memory.