Get overview of potential performance bottlenecks

[thomasp85]

At the moment the event cycle should be a zero-operation unless handlers have been attached. Still, I need to look into the efficiency of the cycle, as well as the event flushing mechanism to make sure it is as performant as possible

[cpsievert]

Relevant example in https://github.com/thomasp85/fiery/issues/34 where the route handler appears to be called twice