I have a JSF2 application that renders a large table with complex content. Unfortunately, each request takes up to 6 seconds to process. Using simple debug output inside a phase listener, I could see that the performance loss distributes evenly over all phases that process the component tree. So I started up a profiler to see what's going on in detail and found out that over 300.000 ValueExpressions are evaluated during one simple request.
They resolve to really simple getters without any logic, so the problem is not executing the code behind these expressions but parsing the expression string and invoking the getter methods. This leads to a few questions:
1.) Is there any way to speed up the resolving of method expressions. Maybe a hidden "enable caching" flag or something.
2.) It seems most of the expressions are evaluated not inside the render response phase, where they are actually needed, but during the other phases. It seems unnecessary to resolve for example styleClass during any other phase than the render phase. Can I prevent this?
3.) Of course, minimizing the number of EL expressions in my facelets page should help getting more performance, but it seems that I cannot really do this: Many attributes (like the styleClass example mentioned above) are actually dependent on the table row, but can only be set on the column. So, having 10 columns, each expression is evaluated much too often. I've seen examples where the rowClasses attribute of the table is used to conditionally style the rows, but as the table is sortable, that won't work without rolling my own sorting mechanism. Is there a better way to implement this?
4.) One more simple question: Is there a way to cache variables in the component tree (just like ui:repeat provides access to the contents of a list and resolves the expression to get the list only once, but just for one variable)?
Thank you ver