Collocations for efficient - adj.

appear, be, look, seem, sound
become
make sth

extremely, fairly, very, etc.
highly, incredibly, remarkably
perfectly
We already have a perfectly efficient system—why change it?

brutally, ruthlessly
He was ruthlessly efficient in acquiring estates.

increasingly
reasonably, relatively
economically, environmentally, technically

at
Their equipment was not as efficient at finding gold as today's machinery.

in
The heating system is very efficient in its use of of fuel.

Efficient is used with these nouns:
administration, allocation, collection, delivery, deployment, exploitation, machine, management, manner, means, method, operation, organization, producer, production, running, service, system, technology, transfer, transport, transportation, use, way