# Prepend $pwd as necessary
@p=();
foreach (split("/", $path)) {
  pop @p, next if $_ eq '..';
  next if $_ eq '.';
  push @p, $_;
}
$path=join("/", @p);

##</code><code>##

Benchmark: timing 1000 iterations of Mikfire, Zamboni...
   Mikfire:  1 wallclock secs ( 0.47 usr +  0.00 sys =  0.47 CPU)
   Zamboni:  4 wallclock secs ( 3.23 usr +  0.00 sys =  3.23 CPU)

##</code><code>##

while ( $path =~ s#(/[^/]+)?/\.(\.)?/?#defined($2) ? "/" : "$1/"#e ) {;}