Trigger latency too high

I have automation to switch power on when temperature drops below a certain point. It works but it switches the power on quite late, after more than 15sec although I can see the sensor reading already dropped pretty soon (within 3sec). What causes the automation delay?

It is a Sonoff basic relay with a thermal probe, Tasmota and 3sec telemetry period.

Anyone? How often does HA check trigger conditions when condition is a template?