Data normalization when control has multiple values in CS/CE
One simple approach is to use the median.  It is less sensitive to outliers than the mean, but still serves as a good summary of typical running time.  Alternatively, you could use the mean but in that case you should inspect all the results yourself to check for the possibility of outliers.  I personally would recommend the median.

Papers often show confidence intervals as well, so that you can assess the effect of statistical noise.

Normally, benchmarks are run on an isolated system to minimize interference from other tasks.

Note that there are many challenges with benchmarking.  Even simple irrelevant changes can cause significant changes to performance, e.g., because they happened to change cache alignment to something that is randomly better or worse.  Therefore, it can be difficult to separate out whether your optimization led to a 3% performance improvement because your optimization is an improvement, or if that's just randomness (e.g., just recompiling with slightly different settings can change the running time by +/- 3%, and you happened to get unlucky once and lucky the other time).