Depending on how rigid the format is, maybe something like this :

use strict;
$/ = "\n\n";

while (my $record = <>) {
    chomp($record);
    # $record contains all needed lines
    # from START OF RECORD to END OF RECORD
}
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If you are planning to have 1000's of line between begining and end, and are really worried about memory usage, you may want to save each start when you encounter it, then if you find the data you want, seek() back. From what i can gather this is similar to what you do now, only without the full scan of the file