Layout implementations with client side performance as a top priority
Default layouts in Vaadin have lots of features. This comes with a performance hit. Performance hit is most commonly negligible, unless you are rendering a vast amount of components. In some cases (like when building long reports) vast amount of components can't be avoided.
FastLayouts is a collection of layouts that perform extremely well on client side. They don't have all the features of layouts in core vaadin, but they may render more than ten times faster than the default layouts in some situations.
Layouts in this package are also easy to theme and a solid base for printable reports.