Investigating the T66802 I realized that there is plenty of room to optimize the Edge Slide.
The current code loop traverses all edges to find the ones selected, and then tests each vertex of the selected edges and then traverses over each linked edge to finally execute the code.
However the list of vertices that are part of selected edges has already been stored in EdgeSlideData through the TransDataEdgeSlideVert * sv member;
Therefore, the loop should only cover these vertices.
And that is the proposal of this patch.

Splited from D5247