reference website: http://windows.microsoft.com/en-my/windows/why-internet-connection-slow#why-internet-connection-slow=windows-7
Why is my Internet connection so slow?
Windows 7 More
No matter how fast your Internet connection is, there are times when things will slow down to a crawl. This article will help you sort out what kinds of things can go wrong, learn what you can do about them, and discover how to get the most from your Internet connection.
Windows provides a built-in troubleshooter that can automatically find and fix some common connection problems.
Open the Internet Connections troubleshooter by clicking the Start button Picture of the Start button, and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Under Network and Internet, click Connect to the Internet.
The type of connection you have makes a difference
The type of Internet connection you use is the most important factor in determining your connection speed. The three most common ways to connect to the Internet from home are dial-up, DSL, and cable. If you have a choice, cable is usually the fastest, but both DSL and cable are faster than dial-up.
Many Internet providers also offer Fiber Optic Service (FiOS), which connects to the Internet using light over an optical network. In your home, you still connect your computer through copper wiring. The advantage of FiOS is that it can provide higher speeds than traditional copper wire connections such as DSL or cable. Some Internet providers offer multiple options, depending on the area you are in. More populated areas are more likely to have FiOS available. Check with your phone company or Internet provider for more information.
If you use a dial-up connection, there are a couple of good ways to optimize your Internet speed. First, use the fastest modem you can. The fastest modem you can use will send and receive information at a rate of 56 kilobits per second (Kbps). You won't get a full 56 Kbps speed most of the time, but with a good phone line, you should approach at least 45-50 Kbps.
Second, make sure that your phone line is in good condition. If the telephone wiring in your home or business is old or deteriorating, you might be picking up stray signals or cross talk from other phone lines. These problems will slow your Internet connection because the modem will have to send the same information over and over until it's transmitted without interruption. Check your telephone wires to be sure they aren't damaged, frayed, or twisted around power or other telephone cables. If you notice crackling in your phones, you might want to contact your phone provider to have them check the lines inside and outside your home to make sure they are in good condition.
Tips for wireless network users
When connecting to a wireless network (Wi‑Fi), your Internet connection speed can be affected by both where your computer is located and whether other wireless devices are in the same area. Wireless networks operate on frequencies that are similar to those used by other devices, such as microwave ovens or cordless phones. Operating a 2.4 gigahertz (GHz) cordless phone next to your 2.4 GHz wireless laptop can cause interference, or completely block the wireless network connection. If you want to make phone calls while surfing the web, either use a wired telephone or a cordless phone that operates at a different frequency than your wireless network.
Proximity to the wireless access point or router, as well as physical obstructions, can affect the quality of your Internet connection. To improve your connection speed, move closer to the access point and make sure that there are no physical obstructions between the access point and your computer.
Computer woes: spyware, viruses, and other programs
The health of your computer can affect your Internet connection. Spyware and viruses can definitely cause problems, but your Internet connection speed can also be affected by add-on programs, the amount of memory the computer has, hard disk space and condition, and the programs that are running.
Two of the most frequent causes of poor Internet performance are spyware and viruses. Spyware can slow your system by interfering with your browser and monopolizing your Internet connection. Spyware monitors your Internet use and keystrokes, which adds delays. The problem is compounded when there are multiple spyware programs running at the same time. If the problem is severe enough, you can lose connectivity altogether. To get your Internet performance back, you should regularly run an antispyware program to clean out any spyware infestation. For more information, see Scan for spyware and other potentially unwanted software.
Computer viruses can also cause poor Internet performance. When a virus infects a computer, it installs computer code which will attempt to propagate itself, usually by sending copies of itself through e‑mail. Some viruses can multiply at the rate of hundreds of e‑mail messages per minute, which leaves little computing power and Internet connection bandwidth for anything else. Viruses often don't give any obvious indication that they are running, so it's best to run your antivirus software at all times. For more information about dealing with viruses, see Viruses: frequently asked questions.
Browser add-ons also cause performance problems. Browser add-ons are programs, such as multimedia add-ons, search bars, or other programs that usually appear on your browser's toolbar. Many browser add-ons can add to a rich browsing experience, offering multimedia or specialized document viewing. However, some add-ons can slow your Internet connection. If you suspect that add-ons are causing slow performance, try starting Internet Explorer in Add-ons disabled mode. Add-ons are disabled only for the session, but if you find your performance improves, you can use the Add-on Manager to turn them off permanently. To access the Add-on Manager from Internet Explorer, click the Tools button, and then click Manage Add-ons. For more information, see How do browser add-ons affect my computer?
Like all computer programs, Internet Explorer requires a certain amount of computing power, memory, and disk space to run efficiently. Every webpage you view is first downloaded to memory and then saved to temporary disk files. Running another program that is using lots of memory and computing power can compete with Internet Explorer and cause delays. If you find your Internet connection running slowly and you have other programs running, try closing them. If you want to run several programs, consider increasing the memory you have on your computer. Low disk space can also cause performance problems. You can increase your disk space by deleting Internet Explorer's temporary files. To learn how to delete temporary files, see Delete webpage history.
Occasionally, settings get changed in Internet Explorer that could possibly affect how Internet Explorer works. You can reset Internet Explorer to its default settings. For more information, see Reset Internet Explorer settings. Resetting Internet Explorer isn't reversible, so you should read the list of settings that are affected before resetting.
Outside factors that affect connection speeds
Unfortunately, there are events and conditions that are outside your control. Even with a fast connection, external factors, such as busy websites or spreading computer viruses, can slow the entire web. Popular websites can become overwhelmed with users. For example, when a television commercial mentions a website, many people might try to visit the site at the same time. If the website isn't prepared to handle the traffic, you might encounter delays.
During times of heavy computer virus outbreaks, the Internet can slow down. Many viruses spread by causing computers to send out hundreds or thousands of copies of the virus. This can slow the Internet by sheer volume. You can see what major outbreaks are currently happening by visiting your antivirus vendor's website, or the Security at Home website.
Local Internet congestion can also result in slower-than-normal connection speeds. These slowdowns occur when many people try to connect to the Internet at the same time, and they occur most often at peak activity times, such as after school hours when students get home and connect to the web.
If you're on a corporate network, general network and proxy server use can affect your Internet performance. Most network administrators monitor Internet use, and will try to keep people from doing things like downloading large files during peak hours. If you find that your Internet access is slow at times, you might discuss it with your network administrator.
