Moving to PHP 7 is kind-of a forced move for us; nonetheless, we need to evaluate how this will affect our users and our infrastructure.
- Does PHP7 add latency to a single request? If so, how much?
- Does PHP7 support the same throughput HHVM can support? If not, how big is the penalty we expect?
Since there is abundant evidence that PHP 7.2 performs better than PHP 7.0, we might want to repeat the experiments once we have php 7.2 available, if the results are particularly bad.