Sngine or any other social network script will use a lot of server resources. Sngine like any other social network use a real-time tech to keep users update to date not just for chat
Shared Hosting is a good starting point but will not the right place to host a growing social network script and you should think to move to a VPS then to dedicated server that will be much better than shared hosting.
To running a social network script smoothly you have 2 things:
1- Very good code with all optimizations and cache system.
2- Good servers to handle this traffic.
Sngine already is optimized in all aspects back-end and front-end; Sngine is #1 on PageSpeed Test from Google
Sngine (95 / 100): https://goo.gl/D2e267
Phpdolphin(86 / 100): https://goo.gl/N3fx7Y
Wowonder (72 / 100): https://goo.gl/cOv6GQ
Socialkit (38 / 100): https://goo.gl/aZdXei
And if you need a client example here it is: http://demogame.org/ with 80,000 users and Alexa Rank of 43K World Wide.
and running so smoothly and fast.
You should think of shared hosting then VPS then dedicated server then Cloud Hosting with auto-scale feature like Google Cloud or Amazon Web Services.