Long response times from Delivery and GraphQL apis


I am working on project for a client who has a Premium Plan. We are using a combination or GraphQL and Content Delivery API calls. For Page/component data we use Graphql, but when filtering, we use the Content Delivery API as the Graphql api did not support filtering as we needed it.
We are running load tests and are experiencing very long response times from both apis. These range from 10 - 25+ seconds. I am not getting any api rate limit errors, so I am not sure what the issue is.