'''MS''': please visit also [Speed of different method dispatching methods]

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The simplest way to call a procedure, namespaced or not, is (1) to give its '''full name''', with arguments. For a proc exported in a namespace, you might also (2) '''import''' it so you call it by 'basename', omitting the namespace path. Also, you can (3) instruct any interpreter that a proc name like ''foo'' is an '''alias''' for another like ''bar'', which may also have constant arguments (minor commands) appended:
 interp alias {} foo {} bar grill
Finally, you can (4) '''indirectly wrap''' a proc invocation in another proc:
 proc foo {x y} {bar $x $y}
[Miguel Sofer] has timed these four alternatives, and to our surprise found out that aliassing (3) takes double the time of (1) or (2), so even (4) is clearly better:
''...on 8.4a2, at least!  On my notebook I get''

 direct       : 299050 microseconds per iteration
 import       : 288499 microseconds per iteration
 interp alias : 638389 microseconds per iteration
 indirect     : 365086 microseconds per iteration

''when I run "t 10000" (a few times, until timings stabilize ...) after defining the script below.''
----
 namespace eval mig {
    proc test {} {set ::a 5}
    namespace export *
 }
 namespace import mig::*
 interp alias {} test2 {} ::mig::test
 proc test3 {} {::mig::test}

 proc t {n} {
    set t1 [time {
 for {set nn $n} {[incr nn -1]} {} {
     ::mig::test
 }
    }]
    set t2 [time {
 for {set nn $n} {[incr nn -1]} {} {
     test
 }
    }]
    set t3 [time {
 for {set nn $n} {[incr nn -1]} {} {
     test2
 }
    }]
    set t4 [time {
 for {set nn $n} {[incr nn -1]} {} {
     test3
 }
    }]

    puts "\n"
    puts "direct       : $t1"
    puts "import       : $t2"
    puts "interp alias : $t3"
    puts "indirect     : $t4"
 }
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RS - I would not have expected such a penalty for an interp alias. What do you others think?