Have you looked at Flux? You can do some really incredible things with it, both inside of queries and also in tasks/alerts. Check out https://www.influxdata.com/blog/anomaly-detection-with-media... for an example

Yes I have looked at it and it's unusable for my application because it is orders of magnitude slower than InfluxQL. Fairly logical if you think about how Flux works, it's very hard to optimize a query engine with a language where every step is supposed to be discrete.

There are actually multiple optimizations to Flux already underway. The language runtime can "push down" some of these operations to the storage layer where they can be performed more efficiently.