Usually it's not the web framework itself that is unable to process the requests, but the web application in which one http request ends up in a few database requests, and the database is the real bottleneck.
By writing something in Erlang does not make your program automagically perform well (and this applies to CouchDB too).
Short answer is no. Most of the "slow" queries that happen in databases are usually complicated select/join/update statements -- the same can happen for key/value databases. Even with TC, you're still programmatically writing the code to do the query and if you write slow code, your query will still be slow. The sweet sweet technology isn't going to magically solve anyone's problems.
By writing something in Erlang does not make your program automagically perform well (and this applies to CouchDB too).