Performance of GC.collect() for single block of `byte`s

[Per Nordlöw]

On Monday, 24 September 2018 at 14:31:45 UTC, Steven 
Schveighoffer wrote:
> It's not scanning the blocks. But it is scanning the stack.
>
> Each time you are increasing the space it must search for a 
> given *target*. It also must *collect* any previous items at 
> the end of the scan. Note that a collection is going to mark 
> every single page and bitset that is contained in the item 
> being collected (which gets increasingly larger).

Is this because of the potentially (many) slices referencing this 
large block?

I assume the GC doesn't scan the `byte`-array for pointer-values 
in this case, but that happens for `void`-arrays and 
class/pointer-arrays right?

Couldn't that scan be optimized by adding a bitset that indicates 
which pages need to be scanned?

Is it common for GC's to treat large objects in this way?