"E-4 has clipped wingtips, F-4 has rounded tips. This gave F-4 bit better turning ability, not much but it was better."
When they first made the Franz, all they did was clip the Emil's wing, giving it a shorter span to improve speed. Unfortunately this gave the aircraft bad stalling/landing characteristics, so they restored some of the lost wing area with the addition of the rounded wingtips. The square-tipped Emil wing actually has more area, but is shorter in span.
"In the book "Fighter" by Len Deighton he has a diagram showing that the 109E3 actually turned better than the spitfireI or Hurricane, despite the higher wingloading."
Muahahaha! Finally someone has brought that one up!

Those figures were calculated, and unfortunately the weight used for the Bf 109E-3 was incorrect - too low. Also the calculations were for a "sustained turn" at an airspeed of 300mph, meaning the fighters would have to pull something like 7-8G to actually produce the given radii, and would need power vastly exceeding the ~1100HP their engines could produce to sustain that speed!