Q: Why do same query on couchdb takes different amount of time ? I have a couch db application and for most of the views I notice that the time taken by the server to return a response varies from 10ms to 100ms. I do not have any concurrent write operations on the server and there are at the most 10 concurrent read requests. 
How should I diagnose the problem ? Where you I look ? 
I am running it on a rackspace cloud machine with 1GB RAM. 

A: From the Couchdb Guide:

If you read carefully over the last few paragraphs, one part stands out: "When you query your view, CouchDB takes the source code and runs it for you on every document in the database." If you have a lot of documents, that takes quite a bit of time and you might wonder if it is not horribly inefficient to do this. Yes, it would be, but CouchDB is designed to avoid any extra costs: it only runs through all documents once, when you first query your view. If a document is changed, the map function is only run once, to recompute the keys and values for that single document.

Most likely you are seeing the views be regenerated and recached.
