We use terraform extensively for deploying our AWS REST API Gateways. Our API’s are pretty big (500+ endpoints per API). As a result it takes hours for our deployment pipeline to complete an update.
We think the slowness is due to the “5 requests per second per account” (with a “Total operations limit of 10 requests per second with a burst quota of 40 requests per second.”) limitation AWS imposes on API calls to API Gateway service .
However we are not sure how Terraform behaves when it tries to call the AWS API to update the API Gateway resources. If we add more parallelism to our terraform apply commands, will it try to send more API calls/second or Terraform is aware of AWS API limitations and plays safe?
The reason I ask this is because we are attempting to ask AWS to up the limit of the API calls/second in our AWS account and we need to be sure Terraform can work well with a higher API calls/second.
 Amazon API Gateway quotas and important notes - Amazon API Gateway