Hi nitendra shukla,
There are many ways by which you can increase the speed of your internet as well as your system. First you need to use quality browser such as Google chrome or Mozilla Firefox that are very efficient. After that you need to delete the cookies and temporary files which are there in your computer system. These cookies and temporary files should be deleted on regular basis as they can result in slow processing of your system as well as internet. Well there is one application called as Cheat engine that increases your downloading speed . This application is easy to use and it free of any cost.
The only way to hack the someone's personal wi-fi is you need to be very expert in coding and encoding. For this there is no such shortcut. I hope this information was helpful to you