Is evasi0n jailbreak free & safe?

Is it free? And is it safe to download it to my computer since im jailbreaking my iphone 4s from my computer. Will it slow anything down (my computer or iphone)

Free? Yes
Safe? Yes
Slow? No (computer), May, very slightly (iPhone)

Oh & if you are on 6.1.3 then don't bother. There is no jailbreak available for that.

Free, yes
safe.no. You cant restore once used