When reading Joseph Conrad's Heart of Darkness, how might the term "efficiency" be defined in the context of imperialism?

Very early in the first chapter of Joseph Conrad’s novel
The Heart of Darkness, Marlow, the character who narrates much of the book, discusses
the fact that Britain itself was once an uncivilized, savage land. He imagines the Roman
conquerors who invaded Britain, and in particular he imagines the reactions of some of
the rather ordinary Romans who must have come to Britain after it had been conquered.
They weren’t professional soldiers; they were citizens visiting the very outskirts of
the Roman empire. These were people (he says to his comrades) who had to encounter
metaphorical darkness and who would have felt the

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“fascination of the abomination--you know.
Imagine the growing regrets [they must have felt], the longing to escape, the powerless
disgust, the surrender, the
hate."

“Mind,” he continues
(meaning “mind you” or “I readily admit”),

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“none of us would feel exactly like this. What
saves us is efficiency--the devotion to efficiency. But these chaps were not much
account, really. They were no colonists; their administration was merely a squeeze, and
nothing more, I suspect. They were conquerors, and for that you want only brute force .
. . .”

This is a crucial
passage. Indeed, only one other explicit reference to efficiency appears in the entire
novel – a fact that gives the passage just quoted special
weight.

What, then, does Marlow mean by “efficiency,”
especially in the context of colonialism?  Here are some
possibilities:

• He seems to distinguish between
  mere conquerors and true colonists (or colonialists). Conquerors use brute force to
  subjugate other peoples so that they may essentially steal from them. Colonialists, on
  the other hand, plan to settle in a foreign country for an extended period of time and
  plan to exploit its resources for the foreseeable future. In order to be effective at
  such exploitation, they must be efficient. They must establish smoothly functioning
  systems that allow them to use the colonized land and people to maximum advantage. They
  don’t intend simply to steal and then leave in a few years; they intend to establish a
  long-lasting colonial enterprise that will repay handsome, dependable, and continuing
  returns on any investment.


• “Efficiency” implies
  planning, forethought, and intelligence. It is not merely the taking of a quick,
  momentary advantage of an opportunity that just happens to present itself. Instead, it
  suggests the use of the power that is necessary to accomplish a preconceived task. By
  the time Conrad was writing, “efficiency” was a word that had come to be often
  associated with industrial production and business acumen. It implied effectively using
  tools (literal or metaphorical) as means to an end, even if those tools happened to be
  human. It implied (and still implies) energy, commitment, and the ability to achieve the
  most output for the least amount of effort. All these connotations, of course, are
  highly relevant to colonialism.


• “Efficiency” in this
  context also implies the setting up of actual established colonies, not mere temporary
  outposts. Colonies would lure colonists eager to profit and perhaps even settle. 
  Efficiency would make a colony the kind of place where one might want to settle for an
  extended period of time.