Performance issues on #Intel CPUs vs #Amd ones

Alexander Peshkoff wrote on Firebird-devel

One of our users, GLDS, has found that firebird 2.5 (64-bit mode) runs on some
very simple tests 2 times slower compared with firebird 1.5. I’ve checked it
on my box and could not reproduce a problem. Afterwards it became known that
my box is amd, in GLDS – intel.

Therefore I’ve decided to compare different versions on different CPUs.
Performance tests showed, that firebird 1.5 runs on them with more or less
same speed (therefore it’s very convenient for comparison). But firebird 2.5
runs really runs on intel almost 2 times slower, than 1.5(and therefore 2
times slower than on amd).
What else required explanation – why do we not
have this performance issue under windows.
[ED: seems that was an NetBust/p4 core with HT on that had these performance issues]