I was testing on an ipad Mini 1 and saw there was a noticable lag when the pathfinding had to do its work. I always knew this was not optimally coded. It also was a lot of code, and a lot of code is hard to optimize. So I integrated another AStar implementation into my game that runs much faster. To notice the lag more evidently I zoomed my map out for a factor of 4 to reach a far away target tile.
Now it runs smoothly on low end iOS 9 compatible devices like the iphone 5 and ipad air and up.
See the difference in this video :