Boto3 client initialization outside handler function / assume_role credentials use case from this solution

[pe-pe]

Hello,

When testing performance of reference solution I've noticed a 200-300ms latency caused by initialization of boto3 client/resource inside handler functions, for example:

https://github.com/aws-samples/aws-saas-factory-ref-solution-serverless-saas/blob/main/server/ProductService/product_service_dal.py

(line 26) get_product function (lambda handler)
   -> (line 27) __get_dynamodb_table
      -> (line 157) boto3.resource('dynamodb', aws* credentials)`

The same approach (and latency) is visible in all other functions using assumed_role credentials.

Following AWS documentation/best-practices, the resource/client initialization should be done outside handler (ref. https://docs.aws.amazon.com/lambda/latest/operatorguide/static-initialization.html), while there is no information how to tell client to use assume_role credentials in such case.

Is it possible to optimize and move boto3 client/resource initialization outside handler in such scenario or optimize the code in different way?