Hi @wdecoster In the last version I submitted, a significant drop of performance using -i or --input for .gz file is observed. I did some modifications to the code to enhance the --input performace, breifly:

1. Use different version of flate2 to achieve the best performance as mentioned in https://github.com/rust-lang/flate2-rs#Backends
2. Add a 512 k buf.
   The performance is shown below:

Which is still worse than system-level gunzip, but close.