[final kaoss]

After you enable https, you most likely will experience a drop in traffic for some time. You can read more about that here.
http://www.seoblog.com/2017/07/rankings-drop-https-ssl/

There are benefits including security plus using less server cpu & bandwidth. Some are

1. is binary, instead of textual
2. is fully multiplexed, instead of ordered and blocking
3. can therefore use one connection for parallelism
4. uses header compression to reduce overhead
5. allows servers to “push” responses proactively into client caches
6. Wait what? Don't worry - let's try to explain this a bit in layman's terms.

Binary instead of textual: this is something which makes transfer and parsing of the data much more efficient. Binary data transfer is also much less prone to errors.

Fully multiplexed: again, simply put, with HTTP the problem was that each connection was prone to blocking the connetions after it. Imagine yourself in the queue to get into your favourite sports match, but rather than having multiple entry points, you only had 1 turnstile. You can imagine that things can get very very slow. Multiplexing allows multiple files and requests to be transferred at the same time. In the turnstile example, rather than have one person going in at a time, we have 10 gates, with 10 turnstiles going in together.

Use one conection for parallelism: as we mentioned before, when a connection is expensive to create, if you keep creating and closing it for every resource you need, you're going to create a serious overhead issue. Multiplexing allows the same connection to be reused over and over again. Imagine the connection as a pipe through which data keeps flowing until you don't have any more data. Also, do note that for any website, you will typically have the browser talking to multiple web servers for various 3rd party scripts and resources (Facebook sharing scripts, Twitter, Google Analtics, Ad networks etc. etc.) Having one connection for each of these is more efficient.

Header compression is also another efficient way of removing several of the overheads associated with having to retrieve several different resources from the same or multiple web servers. Once again, typically rather than having to perform multiple to and fro trips, one trip is typically enough.

Allows servers to push resources proactively: this is a way that the server, rather than waiting for the client browser to request the different resources as per our first example, it will proactively send them resources they will probably need. This is called HTTP/2 Server push.

Thanks to collectiveray for the info.