amd64 slower than i386 on identical AMD 64 system?

[Bruce Evans]

On Mon, 13 Mar 2006, JoaoBR wrote:

> Since some time (>6.0R) I have the impression that amd64 runs slower than
> i386. Now I run some tests on identical hardware and using ubench confirmes
> this. Somebody has comments on this?

Of course 64-bit mode is slower.  Many (data) objects are twice as
large, so there are more cache misses.  64-bit integer registers make
relatively little difference except in code that does lots of 64-bit
integer operations.  Other features that are only available in 64-bit
mode make relatively little difference except in even more specialized
code.

Bruce