hardware acceleration is not just for flash player but it defines the all over the GUI and related things to minimize the effect on the processor. it basically does use the graphic card basic functions to support to render the browser contents this includes GUI interface, flash player,image rendering,HTML 5 (canvas tool,OpenGL contents) and even video player of HTMl 5. in Windows it uses DirectX 9 API and in Linux I think OpenGL. if you got a graphic card which supported DirectX 9 API but still in lower grade you may experienced low performance. then just switch over to processor so you can have a better performance. but this only works if you got these kind of issues.