Methinks you're overly worried about optimising things ;-) So much so that you're making small typos that will cause you no end of headache (well, it'll end if you're using strict... but still be headaches while you sort it out).
ELEMENT: foreach my $key (keys %Contracts)
{
$tot_count++; # hmmm...
{
# lock block
lock @{$Contracts{$key}};
my $Cntrct_ref = $Contracts{$key}; # note: no backslash
next ELEMENT if
$Cntrct_ref->[STATE] eq $ST_VOID or $Cntrct_ref->[STATE] eq $ST_
+REPORTED;
$elapsed_time = time() - $Cntrct_ref->[START];
...
Note the arrows. Much like C/C++'s pointers. Now, as to speed - I think that your first example will outperform the second as long as accuracy is also important. ;-) And that brings me to my point: don't fret about minor details like this. It's much easier to make correct code fast than fast code correct. So, I'd say that you should just get it working, and, if it's not fast enough, profile it and then see where it can be sped up.
You're worried about hash-lookup times in a byte-code language. That just doesn't seem to be a productive use of worrying time to me ;-)
