Still a lot to be said for old technology (HP 432A RF power meter)

It's probably just my ignorance on this subject, but I find it
remarkable how fast this HP thermistor is able to respond to even
minute changes in temperature caused by variations in applied power.
To my eye, the change is instantaneous. The meter needle flicks
between different readings in the blink of an eye as the power is
varied. I'd have expected some degree of thermal lag. I mean we're
talking about only very tiny power levels like -30dbm. How much heat
does that generate into 200 ohms? Yet any change is apparent with zero
noticeable delay.

https://disk.yandex.com/i/gUgUim-KogCOBw