Remove old MacTex distribution

From https://tug.org/mactex/uninstalling.html

The only difficulty is that TeX Live is owned by root and lives in a location that is not commonly visible in the Finder. But it is easy to work around this problem. In the Finder's Go menu, select "Go to Folder"; in the resulting dialog window, type "/usr/local/texlive". You will see folders containing various copies of TeX Live. Drag the folder corresponding to the version of TeX Live you want to uninstall to the trash. You will need to provide an administrative password when asked. 

The folder texmf-local is available for local additions to TeX. These local additions are used by all versions of TeX Live, so if you added files for TeX Live 2014, they are still around for TeX Live 2015. When MacTeX is installed, it doesn't touch texmf-local if it already exists, but it creates an empty directory tree if none is present.

Consequently, if you are updating TeX Live to a new version, you want to leave texmf-local alone. But if you are trying to remove all traces of TeX, then remove texmf-local by dragging it to the trash.

Application asking always authorization for income network

Delete the preference:
/Library/Preferences/com.apple.alf.plist

And restart

Slow Yosemite: check Firevault

I had a problem of very slow computer under Yosemite. In control panel, Security and confidentiality, Firevault was activated but cryptation was in pause for unknown reason.

The solution has been to start in the recovery session (Cmd + R until the apple appears), then choose disk utilities and repair volume and permission after authentificate yourself because disk was crypted.

After a normal startup, Firevault cryptation finished and I could stop it.