Internet stalls, still connected to wireless signal

Whenever I am on my internet browsing it stalls. It always looks connected to my wireless network on my airport. At first the internet works at a normal browsing speed but then after about 2 minutes on the internet the connects will stall or load very slow. I have to stop and constantly reload or re-click links. It doesn't seem to completely drop the connection as I never have to restart the browsing page, just constantly click stop and reload until the page finally loads. I went from an older windows operating system to a macbook pro in october and had not had any problems previously with my wireless internet connection until upgrading to the new macbook. My sister also upgraded around the same time and she too has the same problems. Could it be the router is to old/ slow? All software is up to date. Router is an older netgear. I use safari to browse, my sister uses firefox. both stall and neither load video such as on youtube or facebook. I know it is an internet problem because I also have issues downloading from itunes, i.e. stalls or will just endlessly try to connect to downloads. Any Help please?!?!?!