some nonsense about intelligence because the Japs have higher IQs and outperform Europeans
I never meat such claims, therefore I don't. Western IQ tests are typically done by country than by ethnicity. Therefore when they claim Japanese or other Asians outperform Americans or Russians, it doesn't take in account Americans or Russians could be of any ethnicity.
As a teacher myself, I can tell yout that IQ tests and standardized testing don't necessarily reflect peoples' abilities.
I think the highest known form of human mental abilities are creative abilities. IQ tests don't necessarily reflect their presence directly. Regarding particular people and ethnicities there exist an important difference between creating something new and coping someone else advancements well. I don't know if it related to an ethnic traits or not but if we count Nobel Prize laureates by an ethnicity then N1 place probably comes to people to British ancestry.