This is exactly the case that is better as a result of these optimizations.
[1] I know such a search is ridiculous, but both editors perform search-as-you-type, although atom does attempt to delay that if you type quickly enough. Anyway, it's just an example to demonstrate the speed difference.
Good news, it exists. If you know Go it's possible to see it sooner: http://limetext.org/
The built in search is slow (for now), but they have been steadily making gains and use performance testing to measure progress.