There is a bug, that the file general.php is not always re-created when it is not found. In a setup with 2 servers behind load balancer, one server could be querying the data from mysql at each tracking request. Instead the data should be written on disk on the first cache miss.
Note: see also this related enhancement: - #2830 Tracker cache files should expire to pick up recent changes
In 319b939f5e2ce8090322a81528a5e2ff10384dc7: FIxes #3761 Regenerate cache file on first cache miss
In 8a872c3cec430244bf3e6fe9eaa83c003a798a92: FIxes #3761 Regenerate cache file on first cache miss