I ran this on my machine -- a Dell Precision 340 running Fedora 2.6.something, Perl 5.8.4 --, fixing the arg(s)less problems and giving it a more hefty list to sort (~2500 items). My results from three runs:

             Rate    proto argsless   inline     args
proto    189740/s       --      -0%     -31%     -32%
argsless 190421/s       0%       --     -30%     -32%
inline   273132/s      44%      43%       --      -3%
args     280139/s      48%      47%       3%       --

             Rate argsless    proto   inline     args
argsless 188543/s       --      -0%     -31%     -33%
proto    188746/s       0%       --     -31%     -33%
inline   273988/s      45%      45%       --      -3%
args     281040/s      49%      49%       3%       --

             Rate    proto argsless   inline     args
proto    191010/s       --      -1%     -27%     -30%
argsless 192801/s       1%       --     -27%     -30%
inline   262320/s      37%      36%       --      -4%
args     274019/s      43%      42%       4%       --
[download]

I'm not terribly surprised that inline is faster than the other named sub methods, but am quite surprsied that the 'args' version is the fastest.

Update: Okay, adding an assignment in the benchmarked code gives more sensible results:

           Rate     args    proto argsless   inline
args     17.5/s       --     -45%     -49%     -51%
proto    31.8/s      82%       --      -8%     -11%
argsless 34.6/s      98%       9%       --      -3%
inline   35.5/s     103%      12%       3%       --

           Rate     args    proto argsless   inline
args     17.3/s       --     -46%     -51%     -52%
proto    32.0/s      85%       --      -9%     -11%
argsless 35.1/s     103%      10%       --      -2%
inline   35.7/s     107%      12%       2%       --

           Rate     args    proto   inline argsless
args     17.4/s       --     -47%     -49%     -50%
proto    33.0/s      90%       --      -4%      -5%
inline   34.4/s      97%       4%       --      -1%
argsless 34.8/s     100%       5%       1%       --
[download]