Unless and until some unforeseen, miraculous breakthrough happens in language design, GCd languages will always be slower when it comes to memory management. And because memory management is so critical for complex applications, GCd languages will effectively always be slower, period.
This isn't true. Have a look at Quantifying the Performance of Garbage Collection vs. Explicit Memory Management. The take-away is that GC'd languages are only slower if you are unwilling to pay an extra memory cost; typically 3-4x of your explicitly-managed program. Given that GC gives you safety from null-pointer dereferences for free, I think that's a fair tradeoff for most applications (BTW, you can run the Boehm collector on explicitly-managed code to identify pointer safety issues).
You knew the job was dangerous when you took it, Fred. -- Superchicken