Speedup

```bash
$ time source ~/.bashrc
real 0m0.162s

$ time find $HOME/bin -type l -depth 1 | tr "\n" ':'
real 0m0.010s

$ time /usr/libexec/java_home
real 0m0.020s

$ time source ~/.bashrc_shared/chnode
real 0m0.004s

$ time source ~/.bashrc_shared/chruby.sh
real 0m0.009s

$ time source ~/.bashrc_shared/git-completion
real 0m0.020s

$ time source ~/.bashrc_shared/z.sh
real 0m0.012s

$ time chruby 2
real 0m0.079s

$ time chnode 7
real 0m0.004s
```