I use quick time player. It seems to work better when I don't play in fullscreen and only mark the window I want to capture. And I guess you should make sure to close every program you don't need if it laggs
For me it pops up a window saying that if I push record I will record the hole screen or I can drag and choose where I want to record. Might not be possible on older versions of quick time because I am pretty sure I cant do it on my dads computer. (I don't have quick time pro)
Apologies for the choppiness of the video, don't know how it happened.And took a while to get the butter on to look right, so I didn't feel like re-filming it.