Performance improvements

This is a performance-focused pull request. Primary areas addressed:

* System calls are very, very, slow. When possible, these have been removed by:
  * Using `File#read` vs. `cat FILE`
  * Adding a `:ttl` option to the Disk plugin to throttle needed system calls
* In processes, using `Dir#glob` vs. `Dir#foreach` as `Dir#glob` is faster.