I wonder why having the my inside the block would cause it to use more memory than having it outside?

And even without the my, it still uses 28M:

sleep 5;

if (1) { $foo = "perl" x 1000000;  sleep 5; }
if (1) { $foo = "perl" x 1000000;  sleep 5; }
if (1) { $foo = "perl" x 1000000;  sleep 5; }
if (1) { $foo = "perl" x 1000000;  sleep 5; }
if (1) { $foo = "perl" x 1000000;  sleep 5; }
if (1) { $foo = "perl" x 1000000;  sleep 5; }
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