api gateway: when doest it become a bottleneck

hey folks ive been thinkin about api gateways lately, prob specifically around performance. were runnin a few microservices and use an api gateway to route requests and handle some auth. its been workin well so far, but im startin to wonder at what point does the gateway itself become a performance bottleneck? are there common metrics you watch, or specific scenarios where youd recommend splittin it up or introducin a different pattern? curious to hear your experiences