I don't know if this makes things faster, but whenever I'm using split to split up data, I find it's usually easier to match what I want to keep:

foreach my $line (@arr) {
    if( $line =~ m/^([^=]+)=(.*)/ ) {
        my( $name, $value )= ($1,$2);
        $hashed{ $name }= $value;
    } else {
        warn "Unhandled line '$line'";
    };
};
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This approach also eliminates your substr gymnastics.