This may or may not be directly related to your question, but recently there has been some news lately on ISP's traffic shaping...

That's because there's different types of ISPs, some ISPs are what we call infrastructure based, and that means they build their own networks. But other ISPs may be just a brand, and are paying money for the fibre connectivity in that network, and maybe they can't even afford to buy a whole fibre and they're just leasing per megabit units of bandwidth. So you're going to be more inclined to try and shape your traffic to keep your cost base down.

Unfortunately, if you buy more bandwidth, somebody has to cover the cost of that, so what we're seeing is ISPs introducing tiered services. So for example, given the opportunity for light users to maybe have a metered package, who pay per unit at a time or per amount of data you download, so you can control your own costs as a user, and unlimited packages will inevitably cost a bit more.
Source

Traffic shaping is an attempt to control computer network traffic in order to optimize or guarantee performance, low latency, and/or bandwidth. Traffic shaping deals with concepts of classification, queue disciplines, enforcing policies, congestion management, quality of service (QoS), and fairness.

Traffic shaping provides a mechanism to control the volume of traffic being sent into a network (bandwidth throttling), and the rate at which the traffic is being sent (rate limiting). For this reason, traffic shaping schemes need to be implemented at the network edges to control the traffic entering the network. It also may be necessary to identify traffic flows at the ingress point (the point at which traffic enters the network) with a granularity that allows the traffic-shaping control mechanism to separate traffic into individual flows and shape them differently 1 .

Two pre-dominate methods for shaping traffic exist: a leaky bucket implementation and a token bucket implementation. Both these schemes have distinctly different properties and are used for distinctly different purposes.

In computer networking, traffic shaping works by debursting traffic flows, i.e. smoothing the peaks and troughs of data transmission.

A before-and-after example of how traffic shaping works is as follows.

* Before traffic shaping: 10 packets in one second, 0 packets in the next second, 10 packets in the next second, 0 packets the next second.
* After traffic shaping: 1 packet per 0.2 seconds.

Benefits

When lots of traffic flows past a packet bottleneck (logical or physical) the benefits of traffic shaping are:

* Less jitter.
* Reduced packet loss.
* Lower latency.

Traffic Shaping


So a lot of this will show a variance on whatever speed tests you perform......