Agreed. Honestly I had little to no experience with configuration files like those used in Grunt before a year or so ago, but I don't find anything more intuitive with what I've seen so far with Gulp, than Grunt.
Typical build may look like this: Task 1 passing many files to Task 2, then to Task3, concatenate and so on. It's all about Disk I/O performance. Streams piping reduce files reading/writing.
And Performance? Which Performance? They call tasks that do something, and the task need performance.