Are you also using spring-data-couchbase? First, you need to decide if you want to use the 1.4 SDK or the new 2.0 one. If you want batch import, I’d probably say with async reactive ops in the new one you’ll be better off.
Can you share the code you use so we can take a look?
Also, what are your hardware specs and document sizes you want to store? Json? binary?