config: _fill: inbox name extraction optimization

Using substr() instead of a string copy + s// substitution here
reduces ->fill_all from 4.00s to 3.88s with 50K inboxes on my
workstation.

1 files changed, 1 insertions, 3 deletions

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index 577337dc..cd8957a1 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -424,9 +424,7 @@ EOF
                 }
         }
 
-        my $name = $pfx;
-        $name =~ s/\Apublicinbox\.//;
-
+        my $name = substr($pfx, length('publicinbox.'));
         if (!valid_inbox_name($name)) {
                 warn "invalid inbox name: '$name'\n";
                 return;