Re: how to estimate speed of a transformation

Maybe the point is that optimisations come in many flavours. The 
sum of the techniques used is very hard to predict as everyone 
is saying but some basics can be used as an aid to stylesheet 
coding style. 

I have often resorted to encouraging XSLT developers to use a 
profile tool for the answers, but that is probably just laziness 
on my part, it is easier than explaining the techniques to use 
on the processor I work with.

The Scheme example of requiring an implementation to support tail 
recursion struck me as odd on first reading, but the sense of it 
becomes so clear when you use a language that has no such 
guarantees about its implementations. I have also wondered why 
they just stopped at this one technique, were additional ones 
not very interesting or maybe not general enough to deserve such 
a special rule.

On a more practical note I think a guide of good/bad practice,  
at the "don't create a RTF when a select can be used" level, 
might help somewhat but it could not give the definitive answers 
David appears to want. Perhaps there is a non-trivial language 
where these issues have been well explored for multiple 
implementations but I don't know of any.

Kev.

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