wow! Please send this to perlbug@perl.org.

5.12, with weaken:

1274464820 test 0: main start
1274464820 test 1: func start
1274464820 test 2: func end
1274464855 test 3: main end
[download]

Weaken commented out:

1274464870 test 0: main start
1274464870 test 1: func start
1274464870 test 2: func end
1274464870 test 3: main end
[download]