Very impressive presentation! What data acquisition system did you use to produce this data?
I think the hotter the crystal/ceramic, the softer they become (or the less bound the atoms are to their sites), so a softer spring should have lower frequency. It makes sense.
For windows question, is it possible that the 10ms was set on the TTL USB adapter? FTDI adapter for example, can adjust timeout and other parameters. The adapter doesn't really send serial data immediately after receiving them, but rather do the following two:
1)wait until the receive buffer is full (60? bytes+USB overhead).
2)wait until timed out (adjustable on your PC via the device driver).
To get more immediate response you can reduce the timeout but PCs don't have accurate RTC either, more or less like 1/17 second accurate if I recall correctly but that was from 8086

Someone should update this number.