Contrary to popular belief, Unicode code points are not indexable, so DString does not help. Unicode is glyph based. This + DString being the least beneficent method of storage makes DString not really needed.

When not, the ideal solution is an amortized string walker and light algorithm rewrites. You can create an indexed string walker, that seeks, but if you ask it for indices in order, the seek overhead is basically zero. This is only needed for glyph based algorithms, like case conversion and rendering. Or a traditional string walker without indices, a bit faster, but a lit uglier to use, with Get and ++/-- methods.