Network speed is very slow how do?

Like this:Office has two computers, only to go to work during the day to start, there are houses three computers, will start during the day and late into the night.Cat from the broadband router, the router then two out of two lines of the Office of the computer, Then the third line of more than 100 meters of cable to the switch, and then switch out of the quarters is three computers.'s Earlier speed everything will be all right, even if four or five computers at the same time driving a normal speed, recently did not know how to , During the day when the Office of the hostel computer and computer speed is very slow, IE will have to wait a long time to open the page to display.In the evening, as long as three quarters full of computer, network speed is very slow.But as long as there is a Switched off, speed and a return to normal.In the end is how this is going on? Is not here because of the local area network to connect the computer too much, Telecom was found, was a restricted ah? Or other reasons, ah? Come to help To solve.Thank you,

bandwidth and speed are two different concepts, such as your application is 2M broadband, the bandwidth is to download 2Mbps / s, such as the speed you need to open the website Sina.com 0.5 seconds, which is reflected in the speed, usually, these are likely to slow, one computer problem in itself, and the other is full bandwidth demand can not be caused by transmission, the most common For example, some people download things to occupy the bandwidth 2M, of course, you do not have enough bandwidth to send other data, so I find it very slowly, and the third is the impact the virus, do not say this has been,