drag a rotated shape lead to memory leak

[JRTian]

in the reference, a transformation can be done like below
// if you want you can append or prepend transformations
el.transform("...t50,50");

I think that's the way to move a shape which has been rotated (transformed).
I use this way when dragging a rotated shape then I find the transformation string is getting longer and longer and it leads to memory leak.

Any better way to move a rotated(or transformed) to avoid the memory leak?