Do we need faster regex?

[BoQsc]

The focus should always be on slower but more maintainable and 
simple implementation.

The efficiency and speed should be left for specific cases where 
it is needed and, again with as much clarity as possible.

Support and Features over efficiency and speed.

The question of "is anyone even using that?" is a wrong question.
If it's a common behaviour among implementations, it should exist.

If behaviour makes sense, it should exist and not avoided to be 
implemented just to gain some fraction of speed that can be 
gained in other ways or again, using more specific implementation 
for the job.

If you think that your implementation can be grown into 
supporting all crucial features, then it should be a good draft 
for other people to explore and complete implementation.

Else it should be a specific case implementation that could be 
selected if there is a need for speed but with the sacrifice of 
features.