It probably helped more in 2007 vs. now; modern phones have a bit more horsepower to where they can afford to shrug off a VM. The narrow field of hardware helps significantly in terms of /feeling/ fast if not actually being faster. You'll note that Windows Phones are fairly snappy besides running on effectively year-old hardware and running everything* (including games, WinPhone doesn't support native code) on top of the CLR; since WinPhone only supports two SoCs (the Snapdragon 8x50 and 8x55), MS can pour all their energy into optimizing every last drop of performance out of that chipset.

* There's at least one exception in Trident (the IE rendering engine). Assuming most of the stock apps are CLR-based unless proven otherwise.