hi mate - so, game lag can result from a number of things ... your relative distance to the server, the traffic on the public infrastructure between you and the server, the weather if your country uses satellite or wireless transmission somewhere along the way, your device cache, your device specs ... it is a veritable jungle out there!
so, a couple of tips:
If you are on Android, force close the game, clear the cache and restart the device ... you will need to do this regularly as the Android gaming cache is not FC mobile's friend.
If you are not on android, a restart can help, but is not generally as effective, or if you have done step one and your lag is still bad, then there are a number of other things that you can try for diagnosing connections issues.
Try on a mobile connection rather than wifi
Try both connection types on another device
Move closer to the server (that one is a joke - i am in southern Australia and am so far from the nearest server that the only way i will get a playable h2h match is to move at least 1400kms ... probably more)
connection tips are also here
Troubleshooting EA mobile games on Android devices
Troubleshooting EA mobile games on iPad and iPhone