ColdFusion: does it waste system resources to pass implicit structs as arguments?

ColdFusion: does it waste system resources to pass implicit structs as
arguments?

Bear with me on this...
Say I have an existing struct:
<cfset struct1 = {key1 = "foo", key2 = "bar"}>
...to which I want to add some key/value pairs. The typical approach would
be something like:
<cfset struct1.key3 = "baz">
<cfset struct1.key4 = "qux">
<cfset struct1.key5 = "quux">
Alternatively, I could use structAppend():
<cfset struct2 = {key3 = "baz", key4 = "qux", key5 = "quux"}>
<cfset structAppend(struct1, struct2, false)>
... which has the added bonus of allowing me to control whether
preexisting keys are overwritten. The disadvantage, I assume, is that it
uses more memory since the new key/value pairs will end up existing in two
different places. But what if I do this instead:
<cfset structAppend(struct1, {key3 = "baz", key4 = "qux", key5 = "quux"})>
Have I eliminated the extra memory usage? Or, will the second parameter's
implicit struct continue to exist in some secret location after the
function has executed-- in which case I'm now wasting memory on a
redundant set of keys/values that I can't even access.
Although my primary concern is memory usage, it probably wouldn't hurt to
know if the last approach has any other disadvantages, such as processing
overhead, compared to the first. And I realize that the differences in
resource usage between any of the methods I presented will not be
significant in a single execution scenario. I'm thinking on a larger
scale, with lots of data and/or many repetitions.
I'm currently on CF 9.0.1, if that matters.