Here are a couple of fastest ways to get traffic:
Free Methods:
Guest Blogging: get other people to guest post on your blog and do the same for other blog owners.
Forum Marketing: make sure you provide value or else it won't work
Blog Commenting: same as forums, provide value. Make sure you're the 1st person to comment and only use popular blogs that are updated daily.
Reddit: find a few niche related sub-reddits and post in there, make sure you give back by engaging with the community and you'll get good traffic.
Paid Methods:
Facebook Ads: if you can build your own custom audience then you'll get cheap clicks and to lower your cost even further, keep the traffic within facebook.
Bing Ads: Google Adwords is great but it is expensive so I use Bing instead.
There's a lot of ways one can get traffic but when you say
"Fast Traffic", I think of the methods I just mentioned above. Combining all these strategies is really powerful, try it