The end is where the speed reached the highest, hence the errors. You need to slow your burn speed. Even though they are correctable errors, they are not a good sign. That's why the DVD is so slow. Lower your burn speed until you see no C2 errors. It's even better to use KProbe or CDDoctor to check C1 error levels, and you can "tune in" your burn speed even better. I'll bet your DVD will read them faster if they have lower error rates. Also, you need to feed that burner some TY (Fuji) media to get the best from it at 48x.
Consult the media FAQ for testing info.