You don't have any seriously slow code in that snippet. One comment though; the snippet isn't doing what you stated to be your objective. Instead of splitting columns of a tab-delimited file, it's splitting on any amount of any kind of whitespace. I'm not sure that's your objective.

For example, if your input string contained:

Hello world.\tThis is Dave
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Your snippet would create elements in @Line like this:

@Line = ( 'Hello', 'world.', 'This', 'is', 'Dave' );
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You stated that the objective was to load @Line with:

@Line = ( 'Hello world.', 'This is Dave' );
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