As you said, when using internet on PC our data will reduce mush faster then in a mobile phone. This may be because of the two reason. They are:
1. In computer, there is no compression required as in mobile browsers, so the data to be transferred from a website to a PC is much larger than in a mobile phone.
2. There are some data transfer in the background.
The First reason can be reduced by switch on your caches and cookies. If you're allowing the website to save caches and cookies on your pc,then next time you load the page there will be no need of receiving certain elements from the website. By this, you can reduce the repeated transfer of certain elements. You can also install flash player to load the website mush faster.
For the second reason you must disable those frustrating background processes. To do that Goto Task manager (Ctrl+Alt+Del and click Task Manager) and check the background task which started without your permission. Kill those tasks by right click > End Task.
Note: Do not END SYSTEM TASKS!
You can also open the softwares you installed on your PC and choose never update automatically option on every software.
Now check whether the data is going without any use for you. If it didn't work please reply again to this thread. I will reply you.
Thanks & Regards,
All I Can Do Is Be Me!