How to create A/B test segements for highly variable data
Your ability to detect a difference depends on the relative standard deviation of your data.  Sometimes the noise is due to seasonal effects, which an AB test does an excellent job in correcting.  However if the metric itself is intrinsically high variance, you will need a large sample size, or adjust your significance and power parameters.
Run a check of your standard deviation and do a power calculation to evaluate your situation.
Keep in mind that there are some statistical distributions which have variances approaching infinite.