Sloth
The sloth's approach to efficiency is, paradoxically, extraordinarily refined. By moving at speeds that barely register on standard measuring equipment, it burns a mere 110 calories daily. This creature has solved a fundamental problem of existence: it requires so little energy that it can survive on leaves that would starve most mammals within a fortnight. The sloth is not lazy; it is operating at maximum theoretical efficiency.
London
London processes approximately 1.35 billion passenger journeys annually on its Tube network alone, whilst simultaneously coordinating 32 boroughs, 8 million residents, and an economy worth 23% of the UK's GDP. The city never stops, operating through a Byzantine network of systems that, despite appearing chaotic, maintains a functioning civilisation. Whether this constitutes efficiency or merely organised frenzy remains a matter of philosophical debate.
VERDICT
The sloth achieves its objectives using minimal resources, whilst London requires constant input of energy, labour, and capital to maintain basic functionality. In pure thermodynamic terms, the sloth wins decisively.