Nancy Strauss and Anna Buss’ Online Communities Handbook has some interesting tips for being an efficient community manager.
These including writing clear, updated, FAQs, semi-automating elements of the community (bad word filters), have standard replies to send to members.
There is a simpler solution. If a community manager becomes overwhelmed with the level of work. Hire another online community manager.
If the community manager has been so successful s/he needs help, then hire more. Don't try to change how they're doing the work. They're doing a great job. If you can't justify the budget, then why are you developing a community?