How bad is the performance?
On my PC it's acceptable up to 10 cells and less than 1k ghosts.
The major issue is a lack of events from the core game, so for accurate readings everything has to be scanned each time within a single tick.
See also:
https://forums.factorio.com/viewtopic.php?f=221&t=74375
https://forums.factorio.com/viewtopic.php?f=28&t=72240