If you remember when Mongo first came out, it made a splash with a lot of write focused benchmarks. They were achieved by RAM buffering the writes and then persisting to the disk periodically.

Couch never led in benchmarks and always focused on consistency or both performance and data. That’s not as flashy with the “OMG Benchmarks!” crowd, in my experience at least.

Couch operates entirely over REST last time I checked as well, which makes it a bit clunky for a lot of use cases. Couchbase attempts to be the fast version of Couch and seems to do pretty well.