If we define intelligence as IQ then the evidence is overwhelming that the average differs among races. Even in Singapore, which has a very high standard of living, nutrition etc., we still see Chinese Singaporeans perform significantly better than Malay Singaporeans on various measures of intelligence, with Indian Singaporeans somewhere in the middle. The same pattern is seen among Chinese, Indians and native Malaysians in Malaysia, and globally when we compare the mean IQ scores of China, India and Malaysia.
That could also be explained by cultural differences, I don't think the evidence is overwhelming.
Or it could be discrimination. There are studies that show that black and white mixed races children did not score any higher than children with two black parents, while white people score higher than black people on average, which may point to some discrimination impacting IQ.
Discrimination against whites in favor of blacks doesn't lower white IQ.
There are significant cultural and economic differences between those communities. These will be similar between Singapore and Malaysia. The Chinese and Indians are sufficiently recent immigrants for their culture to still have a lot in common (they speak the same language, follow the same religions, have inherited attitudes) with the places their ancestors came from.