GzipInputStream with SwiftProtobuf

Hello!
I have a protobuf file with multiple messages. I parse them using this SwiftProtobuf method.
Now I want to gzip this protobuf file to reduce the file size.
I found this GzipInputStream implementation (it uses Compression framework). It works, but now file parsing takes ~25% more time than using default InputStream. Is it okay? Or is there something wrong with this GzipInputStream implementation?