The Metadata API has never really been the most optimal API for an IDE, hence Salesforce are now working on the Tooling API (currently in Pilot). So I would not be surprised to see it use more than one, but 24 API requests does seem quite excessive. I have just done a Save and consumed 3 API requests. There is a report you can run to get a little more information.
Click on Reports, and under the Administrative Reports folder you'll find this...
