[pitaj]

As long as it's very consistent, you can use differences

[meejah]

Yes, inter-packet timings are unfortunately pretty good at holding information. (e.g. https://www.freehaven.net/anonbib/cache/stepping-stones.pdf )

Note that Tor doesn't have "global passive adversary" in the threat-model (i.e. an actor that can monitor traffic entering and leaving the Tor overlay).