There *are* memory issues in having very large variables, just as there would be, presumably, in any language. Perl variables take up a lot of space. From perlfaq3:

    When it comes to time-space tradeoffs, Perl nearly
    always prefers to throw memory at a problem. Scalars
    in Perl use more memory than strings in C, arrays
    take more that, and hashes use even more.
[download]

I mean, if you *can* process a file line by line, it's best to do so.