RE: Efficiency: predicate vs function

> For some anecdotal evidence, when I had this exact 
> requirement for the Sudoku Solver [1] and switched from 
> $seq[position() > 1] to subsequence($seq, 2) the performance 
> increase was significant.

That's a little worrying because Saxon is going to a lot more trouble to
optimize the former expression. Looks as if the effort is counter-productive
in this case. There are always cases where that can happen of course (for
example, optimizations to reduce memory usage can be unhelpful if you've got
enough memory not to need them) but I definitely need to investigate why
this is happening.

Michael Kay
http://www.saxonica.com/