The standard perlbench tests did not uncover a cause: Overall 5.8.0 with threads performed about 15% slower than 5.6.1. The only serious areas of slowdown (see below) were for startup costs --- but since that cost is amortized over the runtime of the wc.script, it wouldn't account for the large spread. So I added another directory of tests (xtra/) to test length and split (and open and join) to see if they were the cuplrits (since basic arithmetic had been tested and though the threaded result wasn't pretty, it couldn't account for a 50% relative difference).

The length test showed no big surprise, and while the open is very much slower in 5.8.0 (moreso in the threaded version), it is hardly a factor as only one file was opened when I tested the wc.pl script. (Note: both 5.8.0's were compiled with perlio support, and 5.6.1 was not). Notable, however, is the result for split --- a *very* sizable slowdown for 5.8.0-threaded, and the causative factor of the greater than expected slowdown. Replacing the split call in wc.pl with a constant array and I only saw a 5% difference between 5.6.1 and 5.8.0-threaded --- which is somewhat less of a difference than I might have predicted after viewing the perlbench results.

Someone else might review the 5.8.0 source to see what happened to split and if anything can be done to improve the performance of such an oft-used routine --- as for me, now that I've got two shiny new 5.8.0's, I'm off to CPAN to start fetching packages ...

## results of perlbench 
## NOTE: 5.6.1 used -O2, while both 5.8.0's used -O3 (those were the
## defaults for each version). 
## Platform is: Linux 2.4.18

A) perl-5.006001
    path        = /usr/local/bin/perl5.6.1
    cc          = cc
    optimize    = -O2
    ccflags     = -fno-strict-aliasing -I/usr/local/include -D_LARGEFI
+LE_SOURCE -D_FILE_OFFSET_BITS=64
    usemymalloc = n

B) perl-5.008
    path        = /usr/local/bin/perl5.8.0
    cc          = cc
    optimize    = -O3
    ccflags     = -fno-strict-aliasing -I/usr/local/include -D_LARGEFI
+LE_SOURCE -D_FILE_OFFSET_BITS=64
    usemymalloc = n

C) perl-5.008
    path        = /opt/bin/perl5.8.0
    cc          = cc
    optimize    = -O3
    ccflags     = -D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/u
+sr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
    usemymalloc = n

                           A       B       C
                        ----    ----    ----
arith/mixed              100      76      71
arith/trig               100      88      85
array/copy               100     100      99
array/foreach            100      86      71
array/index              100      89      82
array/pop                100     102      83
array/shift              100     104      83
array/sort-num           100      91      63
array/sort               100      96      69
call/0arg                100     103      93
call/1arg                100      93      82
call/2arg                100      91      81
call/9arg                100      96      88
call/empty               100     102      95
call/fib                 100     102      91
call/method              100      94      91
call/wantarray           100      97      83
hash/copy                100     115     108
hash/each                100     103      94
hash/foreach-sort        100     100      96
hash/foreach             100     106      99
hash/get                 100      94      79
hash/set                 100      85      81
loop/for-c               100      94      88
loop/for-range-const     100      94      82
loop/for-range           100      91      81
loop/getline             100      88      85
loop/while-my            100      91      86
loop/while               100      91      84
re/const                 100      97      93
re/w                     100      94      74
startup/fewmod           100      62      43
startup/lotsofsub        100      95      60
startup/noprog           100      87      68
string/base64            100     102      94
string/htmlparser        100      98      80
string/index-const       100      99      93
string/index-var         100      90      88
string/ipol              100     106      99
string/tr                100      99      99
xtra/join                100     100      96
xtra/length              100      96      87
xtra/open                100      72      44
xtra/split               100      74      41

AVERAGE                  100      94      83
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The code used to test split is as follows (stored in "t/xtra/split.t" under perlbench):

# Name: Simple split
# Require: 4

require 'benchlib.pl';

$_ = "this is just an ordinary string to test with."; 

&runtest(1,<<'ENDTEST');
    my @words = split;
ENDTEST

__END__
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