|laziness, impatience, and hubris|
Does KindaPerl6 use Rakudo?
No. At the time kp6 was started Rakudo wasn't even close to usable.
Its also a bit worrying that there are so many projects - doesn't this dilute the efforts and slow down progress?
Yes and no. Many of these projects have a different focus, and thus they help exploring the specs in different directions. For example one of the design goals of kp6 was to get BEGIN blocks right, smop explores meta object programming, elf focuses on the grammar and parsing.
I don't know if progress was faster if all focused on the same implementation, but in the end everybody can decide what do to with their time.
I hope that Perl6 won't be slower than Perl5 - one of the bad things about Ruby is the lack of speed.
You have to be aware that there are two kinds of speed, one manifesting in short compilation time, the other in short run time.
I would be very surprised if any Perl 6 implementation could keep pace with perl 5's compilation. It's just blazingly fast due to some very evil hacks, for example it doesn't generate an abstract syntax tree. On the plus side some implementations (specifically rakudo) might implement precompilation of modules, which would somewhat reduce compilation time of a given script.
Regarding run time speed, I guess that an initial Perl 6 release will be slower than perl 5. That's because perl 5 has some years of optimizations behind it, which rakudo and other implementations will certainly lack.
But note that Perl 6 is designed with great care to allow many kinds of optimizations. For example the optional static types can allow some very radical optimizations - if some numbers are declared as Int, you can compile down infix:<+> to a single CPU instruction - you can't in perl 5, because you have to beware of overloading and tied variables, and because you can't declare any types.
Also note that rakudo compiles stuff (indirectly) to parrot byte code, and parrot has JIT which perl 5 lacks. Now with JIT you can do all kinds of clever optimizations that you simply can't in perl 5. Optimizations in parrot will benefit all high level languages running on it, so there's great incentive to implement them.