As Don said, B, if it is a good connection, is "fast" enough for anything you get off the internet. It doesn't matter if you have speeds of 100 meg, if your internet connection is only giving you a 5 meg download speed. It might make a difference if you are transferring files on a Lan, but not what is coming from the internet. Once again, as Don said, if you are some distance away from the router, if something is causing interference (microwave, wireless telephone), or if the signal is being shared by more than one computer, those things can all slow the signal down. This is why I have stopped using wireless on my desktops and run cable to them. I've even run cable to where we quite often use the laptops so they can be plugged in. The wireless signal that is used most often is between two bridged wireless access points, to connect my home network with my office network next door. That signal can't be shared.
BTW, in some situations a "repeater" can come in handy to strengthen a signal. However, the "strengthened" signal comes at a price. Your speed will drop by half.