Yes it will be (at least on WinARM) since only IE10 on those will be able to use JIT for JS (do you remember disparity betwen IE9 32bit and IE64bit JS perf? Yeah that will be it)
On the other hand on the WinIntel things will be as usuall. MS will publish good (as for IE) web browser and then after 6 months ANY advantages IE had will be incorporated into competition, which will leapfrog it, and will keep doing it for nest 18 months. (And as usuall IE will NOT be able to be the best at everything)