Obviously we can expect a performance increase similar to what we saw when Intel went from Katmai to Coppermine. Lately Intel has been pushing the integer benchmarks again, since even the old Athlon leaves Pentium III far behind in any pure floating point benchmark. In integer benchmarks, Coppermine Pentium III was able to surpass Athlon and that's were we expect the most improvement of Thunderbird. Let's see if AMD was able to do it.
The performance increase that Thunderbird can show over its predecessor is able to fulfill the expectations. AMD's new processor is almost 9% faster than the 'old' Athlon in Sysmark2000 and therefore just as fast as Intel's Pentium III with Coppermine core, unless you are using the overclocked BX133 or the expensive i840 platform for the Intel processor.