can files on cloudflare disappear and what about performance

So i'm new in the web development world. But for some plugins i use at angular i notice that some use cloudflare.

like this :

<link rel="stylesheet" href="http://ift.tt/1MEff6v">

So my question is should i download the files just in case or will they be permanent online ?

And will this improve the speed of my website if u use cloudflare or is it just the other way around. because i notice that some files are not using a compact css file.