Unless your input file is quite small, consider not using Tie::File for reading it, as it's notoriously slow with 'large' files:

• "Doing the same thing with Tie::File takes 12 times longer"
• "Please do not suggest the use of Tie::File for use with files bigger than a few tens of megabytes."
• "I'd used Tie::File in the past, but not with files this large."
• "I think that using Tie::File in this particular case (when sequentially iterating over the records) doesn't provide any advantage over simply reading line by line from a normal file handle (rather, it's likely to be slower, due to the much more complex things going on under the hood...)."