Which solution meets these requirements?
Change to asynchronous Lambda function invocation.
Cache the translated newsletters in the Lambda/tmp directory.
Enable TranslateText API caching.
Change the Lambda function to use parallel processing.
Explanations:
Changing to asynchronous invocation would not improve response time in this scenario, as it does not address the bottleneck of querying the overloaded database. It merely alters how the Lambda function is triggered without improving database performance.
Caching the translated newsletters in the Lambda/tmpdirectory allows subsequent requests for the same newsletter to be served from memory rather than querying the database and translating again, significantly improving response time.
The TranslateText API does not have built-in caching capabilities. Even if translation requests are made for the same text, they will be processed anew each time unless implemented externally, thus not directly improving response time.
Changing the Lambda function to use parallel processing may help if multiple independent tasks need to be performed, but it does not reduce the response time for the single database query required to retrieve the newsletter, as the bottleneck remains the overloaded database.
I estimate that the answer is:
Cache the translated newsletters in the Lambda/tmp directory.