Asynchronous API's and monotonicity

Hi Zookeeper Users,

Lately, I have been working on a research project where I want to use zookeeper as a distributed logging service.

I want to build a queue on top of zookeeper (also provided in recipes).

What for:
Intention is to insert some operations performed by different clients in a distributed queue, and process them lazily at some later point of time. And I want some ordering between these operations.

Setup:
5 physical zookeeper servers

The problem is:
In my current setup, I am observing a latency of about 13 ms per enqueue operation (using synchronous create APIs with sequential flags). I want to significantly reduce this time. The other way could be to use asynchronous zookeeper calls but I am not sure what can be the side effects. Would it still be monotonous when used with SEQUENTIAL flag?

For example, a client X created a SEQUENTIAL node Z1 at time t1 using async create, same client created another SEQUENTIAL node Z2 at time t2 where t2 > t1. Would the monotonic number associated with Z1 be lesser than that of Z2?

Your help is much appreciated.

Thanks
Mudit