Due to any one of the following reasons your internet gets slow down ;
1. Local network is overloaded
2. Malware or scareware on end users computers
3. Bad connection
If you want to speed up your internet connection , use the following tips :
1. Clear cookies from your browser
2. Close unwanted background tasks when you are working with the internet .
3. Scan your internet by using standard Anti-virus software
4. Reset your modem and reconnect with the internet.
After that , you can test your internet speed by using
Scanmyspeed.com to test your internet speed .