Speeding up typesetting

??=[basics.speeding] One thing that you will notice is that -pic is sometimes slow in typesetting diagrams (this is to be expected considering the number of drawing operations performed as reflected by the number last in each |xymatrix| message). You can instruct -pic to save the details of a particular diagram in a file "name"|.xyc| (for `compiled -pic') every time the diagram changes by replacing the || command with
\begin{defs1}
\vert\diagramcompileto{\vert''name''\vert}\vert
\end{defs1}
This will cut the typesetting time considerably whenever the diagram is retypeset without change.

: this is only safe for diagrams that obey the following restriction: "all entries should start with a non-expandable token" like an ordinary (non-active) character, ||, or ||.

This is a "v3" feature mentioned here because it is a common question.