Asian Americans, in recent years the fastest-growing segment of the population, now generally outperform other minorities and whites in the classroom and the workplace and are "often perceived as a model minority," according to a study released yesterday.

The Population Reference Bureau, using Census Bureau data, said that in general Asian Americans earn more money than white Americans and are more likely to finish high school and college than their white counterparts.

The only category of Asian Americans who perform below these standards are the latest wave of Vietnamese immigrants, the so-called "boat people," who arrived in the United States in the last decade with less education than previous waves of immigrants.

The recent wave of Asian immigrants is helping to transform the U.S. immigrant population, the report said. From 1980 to 1984, 48 percent of all legal immigrants came from Asia, compared with about 12 percent in the 1960s. During the 1980s, a third of legal immigrants have come from Mexico or Latin America while only 12 percent have come from Europe. This represents a sharp reversal from earlier immigration patterns.

Asian Americans have a remarkable record in education, the authors say. Except for Vietnamese students, 1980 high school completion rates for Asian-American males between the ages of 25 and 29 outstripped the 87 percent rate for whites and the 74 percent rate among blacks.

Among Japanese Americans, the completion rate was 96 percent; among Chinese, 90 percent; among Filipinos, 89 percent; among Koreans and Asian Indians, 94 percent. The rate for Vietnamese Americans was 76 percent.

The figures for female Asian Americans in the same age group were good, but not as high as among males.

The 1980 census found that 35 percent of Asian Americans age 25 and older had graduated from college -- twice the proportion of whites.

Chinese Americans led the way in college attendance, with 60 percent of those between the ages of 20 and 24 enrolled in school. For Japanese Americans the figure was 48 percent; for Vietnamese Americans, 42 percent; and for Korean Americans, 40 percent. The lowest group was Filipinos at 27 percent, still higher than all non-Asian groups.

The study said that the 1980 median family income for the six main Asian-American groups was $23,600, exceeding white families ($20,800); Japanese were highest at $27,350 among the Asian Americans. This result, however, was in part due to the fact that Asian Americans tend to live in larger family groupings and have more workers per household.

The report said that Asian Americans generally have lower unemployment rates and higher labor force participation rates than whites or blacks.

The nation's Asian Americans now number 5.1 million and are headed for 10 million by the end of the century, the report said. About 21 percent of Asian Americans are of Chinese origin, 20 percent Filipino, 15 percent Japanese, 12 percent Vietnamese (the fastest-growing group), 11 percent Korean and 10 percent Asian Indian with small groups from elsewhere in Asia.

Over a third of the Asian Americans live in California, 13 percent in Hawaii and 9.4 percent in New York, with substantial groups in Illinois, Texas, New Jersey and Washington, and scattered communities elsewhere.

The authors offer no general theory to explain why Asian Americans, except for Vietnamese immigrants, are doing so well. But one of the authors, Robert Gardner, visiting scholar at the Population Reference Bureau from the East-West Center in Hawaii, said in an interview that part of the explanation may be that a high proportion of Asian immigrants since 1965 have tended to come from the better educated, higher occupational classes of their home countries, bringing a high level of skills and motivation.