and your code thus is equivalent to

use Shell qw( perl );

BEGIN { Shell->import( qw( dir ) ); }

BEGIN { Shell->import( qw( copy ) ); }

BEGIN { Shell->import( qw( del ) ); }

BEGIN { Shell->import( qw( cd ) ); }
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May be worse:

BEGIN { require Shell; Shell->import( qw( perl ) ); }
BEGIN { require Shell; Shell->import( qw( dir ) ); }
BEGIN { require Shell; Shell->import( qw( copy ) ); }
BEGIN { require Shell; Shell->import( qw( del ) ); }
BEGIN { require Shell; Shell->import( qw( cd ) ); }
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Despite that only the first invocation of require compiles the module, it's still a sequence of invocations on the same function (require) with the same argument (Shell) within inside the very same file.