I am a feeder to FA using a Raspberry.
What i have identified is a delay in showing the aircraft on the FA map compared to my local map.
The difference are several nautical miles. Once a flight passes my location, it’s shown on same position on my local map. But on the FA map the aircraft is several miles “behind” it’s real track.
It’s mostly a combination of the web track refresh interval + the web map animating to be at the current position at the time of the next expected refresh, which is a design decision that prioritises a smoothly animating track over latency. The actual end-to-end latency is single digit seconds.