Are there any CSS replacement proposals that are based on linear programming [1]? There are a lot of things you cannot solve with just LP (e.g. rearranging floats on a page) but it's a pretty good -- and simple -- abstraction for laying out boxes relative to each other.
Solving LP is fast, especially when many of your constraints are equality constraints (as would be when specifying tables).
I think Cassowary [1] is what you're talking about (particularly section 1.2 where they talk about some modifications to make their system very fast for incremental updates). Apple has based their constraint-based layout system, Autolayout [2], on Cassowary. There's also a project that incorporates Cassowary constraints into a CSS-like declarative syntax called GSS [3].
Solving LP is fast, especially when many of your constraints are equality constraints (as would be when specifying tables).
[1] http://en.wikipedia.org/wiki/Linear_programming