Motion Blur w/ x and y directional blur.
It's a pretty cool effect but when you enable it the affected layout/layer/object gets slightly brighter. Therefore it doesn't look right when you switch it on or off when you are e.g using nitro in a racing game etc.
Good point, at some point I will look at fixing that meanwhile, if you are interested in using it now, you could add another effect Brightness to make it less bright when the effect is on. Obviously not a great work-around, but if you want to do something right now.
True, that would work… however, I am developing for mobile devices and such effects do affect performance a lot.