Build multiple circuits and use the fastest?
This mostly applies to a usecase such as tor2web where you have a lot of requests in a certain time frame. It might be a good idea to have more than one active circuit towards a certain hidden service (the top 10).
By building more than one circuit towards a hidden service you are then able to collect some benchmark data with all your active circuits and determine which are the fastest ones and which are the slowest.
The benchmark collection and optimization of circuits by speed could be useful also for the normal user of Tor HS, however it might have some bad anonymity consequences.
Q: Is it a bad idea to discard slow circuits towards Tor HS and keep only fast ones?
notes: Keep in mind that you have no control over the circuit on the Hidden Service side and that building a new circuit takes quite a lot of time.
Q: What privacy implications does such a feature have?