When creating a UStringImpl copying of a UChar*, we can use an internal buffer, by calling UStringImpl::tryCreateUninitialized().
Created attachment 46644 [details]
~0.5% progression on SunSpider
Comment on attachment 46644 [details]
r=me, you should remove "Need a short description and bug URL (OOPS!)" from the changelog however :)
Committed revision 53323.