Major performance problem with std.array.front()

[ponce]

> - In lots of places, I've discovered that Phobos did UTF 
> decoding (thus murdering performance) when it didn't need to. 
> Such cases included format (now fixed), appender (now fixed), 
> startsWith (now fixed - recently), skipOver (still unfixed). 
> These have caused latent bugs in my programs that happened to 
> be fed non-UTF data. There's no reason for why D should fail on 
> non-UTF data if it has no reason to decode it in the first 
> place! These failures have only served to identify places in 
> Phobos where redundant decoding was occurring.

With all due respect, D string type is exclusively for UTF-8 
strings. If it is not valid UTF-8, it should never had been a D 
string in the first place. In the other cases, ubyte[] is there.