Just to update this thread, the main issue appears to be a current limitation in Couchbase Admin Console per Aleksey here: https://www.couchbase.com/issues/browse/MB-12356
Conclusion:
So basically avoid using the Documents UI in production altogether since it could possibly impact server performance for clients in production?
Yes.
Are older versions like 2.2 and 2.5 also affected by this?
Yes. Even more than 3.0, because 3.0’s implementation is more optimized.