In the "old" times (in the early 2000s), the low speed of dial-up modems was enough for most people. Now high-speed Internet has become a necessity. But often even on an unlimited tariff and a broadband connection, the speed suddenly drops. How to find the reason?
If the Internet began to work slowly, then first of all, you need to figure out which specific programs “slow down” it. In the minds of many people, the Internet is firmly associated with the browser - the program with which websites are viewed. But the mail program, ICQ and Skype also go online. They also transmit and receive packets of information from their servers and other nodes.
Check their work and if the speed dropped only when working in the browser, then the reason is in it. The easiest way to solve the problem is to install another browser or update an already installed one.
Meticulous people can be offered to understand the settings of the old browser. They can crash for a variety of reasons. You need to look at the "Connection Settings" tab. Here is one of the common mistakes in setting up: there is a checkmark next to “Internet access through a proxy server” and the browser sends all its traffic through an additional server, which affects the speed of loading sites. Try disabling the proxy server and check your internet speed.
Another reason is plugins that limit the speed of the browser. Rate limiting options are found in some types of plugins, such as download managers, or the plugin may simply be "buggy". Try disabling all plugins in the browser, restart it and check the speed.
If automatic updating is set in the operating system settings, then it can be updated at any time at will. The operating system sometimes loads a ton of information, which is not always needed. During such a download, both the Internet connection and the general operation of the computer slow down. To avoid such freezes, it is convenient to install all updates manually. This video shows the process of disabling updates in windows 7:
The following video talks about two ways to disable updates in windows 8:
Many programs like to update automatically: Adobe, Google Chrome, Photoshop. During the download, the bandwidth of the channel is always reduced - after all, part of the channel is occupied by updates. You can disable the automatic update function in the program settings.
If you do not have an adequate antivirus program, then with a high probability you can say that the Internet is slow due to the active activity of viruses. Malicious programs, having settled on the hard drive, begin to download considerable amounts of information, as well as send spam from the computer. To fight viruses, you need a licensed anti-virus program. Unlike other programs, it requires daily updates. Otherwise, the antivirus will be of no use.
When the browser opens pages for a long time, it is useful to carry out a deep scan not only of the system C: drive, but also of all other drives. The free CureIt utility from Dr.Web (freedrweb.com/cureit/) and the free anti-virus program AVZ (z-oleg.com/secur/avz/download.php) do a good job of checking. 
The problem may be on the side of the hardware through which your computer is connected. Often, due to a power surge in the network, a switch or router can freeze. Try rebooting them by turning the power off and on.
It is a little more difficult to check the cable - it often happens that the cable is damaged due to mechanical impact on it, but such damage cannot be determined by eye. For example, they often stepped on the leg of a chair or crushed the cable with a door.
To check, it is best to “ring” the cable with a special device - a signal will be passed through the cable and damage will be determined. This service can be obtained from computer repair companies or from the support of the provider.
If the Internet speed is low only at certain times of the day, or under certain weather conditions - thunderstorms, snow, fog, then most likely the provider's equipment is to blame. It may not be installed correctly, it may flood with water, or it may simply not be able to handle the load during the evening hours. There are two ways out - contact the provider and wait for the problem to be fixed, or change the provider.
If you use a Wi-Fi router to connect, then the reason for the low speed may be interference from a radio or microwave oven - Wi-Fi networks are quite sensitive to such interference. Try switching to a wired connection.
What to do if you have checked all the above options, but still the speed is lower than stated in the tariff? One of the frequent reasons is the "secrets" of the provider. Some fares have speed limits under certain conditions.
For example, if during the month the user managed to download a certain amount of data. When concluding a contract, the provider must say this, but ... Sometimes the user himself forgets about these restrictions. To “treat” such a case, you need to change the tariff. Or maybe a provider.
It happens that the Internet works fine, but the downloaded torrent does not download, or it does it at a very low speed. Downloading from a torrent resource is not like downloading from a server. On torrent sites, files are downloaded from the computers of other people registered in the system. If the torrent is slow to download, it means that it is being distributed slowly from other computers.
What determines the distribution speed? Mainly on the number of seeds. Seeds are all those users who have the file you need on their computer and who distribute it in the torrent system. The fewer people there are, the slower the file will load. And vice versa, when a video, audio, book is very popular and is distributed to a large number of people at once, then downloading them will turn out to be “flying”. If you need to download something rare and large in volume, then it is better to leave this procedure overnight.
