InfluxDB is pretty good if you don't need to do any advanced querying like grouping by month or formulas. Its strong points are low diskspace footprint and very fast queries even over long periods of time.
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.
