Have you considered existing scientific columnar data storage formats, like HDF5 or Parquet?<p>Their main advantage is that they have good, mature implementations in a variety of languages, which would be handy if you ever find Javascript to be too slow.
It's amazing just how much of a loaded word "telemetry" has become in the past few years --- 10 years ago it'd just remind me of space missions and such, like in the article, but now I associate the word more with pervasive surveillance and privacy invasion.