We could improve textPath layout performance by supporting a new path traversing mode. The new mode should take a vector of lengths and should return a vector of arrow vectors (position and normal angle). The input vector of lengths represents the distance from the beginning of the path to each character should be displayed. The output vector of arrow vectors represents the physical character display points and angles (which are needed for rotating the characters). This will require changing SVGTextLayoutEngine to calculate the lengths of the characters on the path first and then passing all of them to the path traversal function. Instead of traversing the path for every length, we are going to get the required point and angle from the vector of arrow vectors.
<rdar://problem/20546814>