There are lot of factors that affects your speed like router problem,Simultaneously if you run lot of software's,There may be a chance of virus attack in your system etc..So try to check everything and all.
If you have slow speed,Try to keep in mind the following instructions
1.Get a download accelerator
2.Turn off all unused apps while downloading
3.Don't upload information while you're downloading
4.Make sure your router is free of any interference
5.Update your network device driver
6.You must always keep your computer clean of any viruses
7.clear your temporary download history files.
8.Use latest version of any browser
9.Do regular speed test.
When i had the same problem,i followed the same ways.I am sure,it's very useful to increase your speed.Then you can check your new internet speed using ScanmySpeed.com