Are you saying that the ‘ptx tilemaps’ extension degrades performance, or that tilemaps in general can be sluggish when it is large and/or contains many sprites?
I posted an issue some time ago, Help with floating sprites, where Richards mentions that large tilemaps, perhaps the number of sprites, and scrolling around, but I am not sure what I need to do to stop the sprites floating. I can make the tilemap smaller and have less sprites, but whatever I do the problem still occurs (even on a mobile phone). I don’t feel like I have a definite explanation on what is causing the problem. Would you be able to elaborate?