Fascinating reference. Thanks for the heads-up.

But it doesn't address the question at all, except for a short textual note about smallest derailleur sprockets being the least efficient.

I guess am most curious about which features of a singlespeed (or derailleur for that matter) drivetrain are most or least likely to be detrimental to efficiency, and to what comparative degree---especially as to what 'mistakes' in setups may be most damaging to performance.