$ alias tperl="time perl -w -Mthreads -Mthreads::shared"

# No data to copy:
 $ tperl -e'threads->create(sub{})->join() for 1..100'
 $ tperl -e'threads->create(sub{})->join() for 1..100'
CPU 0.680 secs (CPU 0.256 secs)

# Load the data late so also no data is copied:
 $ tperl -e'BEGIN{threads->create(sub{})->join() for 1..100}my @x=(1..35_000)'
CPU 0.728 secs (CPU 0.268 secs)
 $ tperl -e'BEGIN{threads->create(sub{})->join() for 1..100}my @x;share(@x);@x=(1..35_000)'
CPU 0.840 secs (CPU 0.364 secs)

# Overhead of copying, whether shared() or not:
 $ tperl -e'my @x;share(@x);@x=(1..35_000);threads->create(sub{})->join() for 1..100'
CPU 2.272 secs (CPU 1.316 secs)
 $ tperl -e'my @x=(1..35_000);threads->create(sub{})->join() for 1..100'
CPU 3.304 secs (CPU 3.384 secs)