Why is ShowGridLines so slow?

Question

I have noticed that enabling ShowGridLines on a Grid causes a huge performance hit.

I have a Grid within a ScrollViewer . When I scroll manually, the application runs fine. However, if I scroll programmatically, using a timer to scroll smoothly, it runs very slow with ShowGridLines on.

With ShowGridLines off , the scrolling completes in less than 1/2 a second as expected. With ShowGridLines on , the scrolling takes 2-5 seconds and jerks unpredictably.

Why would ShowGridLines cause such a performance penalty? Why would it not do so when scrolling manually? Is there a way around this?

Answer 1

The ShowGridLines property is not optimised for runtime as it is intended to be a design time tool only.

From the documentation:

Enabling grid lines creates dotted lines around all the elements within a Grid. Only dotted lines are available because this property is intended as a design tool to debug layout problems and is not intended for use in production quality code. If you want lines inside a Grid, style the elements within the Grid to have borders.