Does the Safari web browser use-up more quickly a dongles download capacity?
There should be very little difference in the way network traffic is handled between browsers as this is mostly handled by the operating system; at least not a scale that will affect your wireless connection. The thumbnails on the home page of safari are sometimes reloaded, so this may use slightly more bandwidth than other browsers. The difference should not be noticeable unless you are on a very restrictive bandwidth plan (i.e. if you are using a mobile network’s GPRS or 3G network without a data plan). If your network connection is running slow, I would suggest this would be for some other reason and you should see if you experience the same issues when connecting to your router with a patch cable. If your bandwidth usage is higher than it should be, try disabling any update services on your system.
The simple answer is yes, if you open more web pages then you will “use-up more quickly a dongles download capacity”. This will be true on any web browser that supports multiple pages per Window (aka Tabs), i.e. Chrome, Firefox, etc. Btw, you’re better off using Chrome or Firefox since Safari isn’t as secure or stable as the others.