Users often run into performance problems early in using MongoDB. Can we make this page below give broader guidance than just query performance (can link to a query performance page)?
http://docs.mongodb.org/manual/applications/optimization/

It actually looks like this page was broadened a bit but it could even go further with these items:

• Journal on a separate disk
• Increase the number of connections in the driver until they don't get better throughput
• Batching on insert
• WriteConcern and changing that depending on batching or individual documents
• Indexes
• Using Mongostat to diagnose the issue (in particular if Mongo is even working hard)
• Pointing out it could be disk bound and typical throughput ranges of different types of disks
• On initial load, turn off the journal and the balancer and create indexes afterwards