Swiss Prosperity on Slippery Slope : Wealth: Conditions shift beneath the top standard of living. European Community membership is seen as a must.

The average Swiss must work a mere 20 minutes to earn enough to buy a hamburger and french fries. The average American worker would have to put in 26 minutes; a Mexican would labor nearly four hours.

The Swiss are wealthier than most others, by average salary, by gross domestic product per capita and by relative fast-food prices. Many Swiss are worried that that may be changing, however.

An economy long built on low inflation, full employment and a stable currency is at bay. Switzerland’s unemployment rate currently is the highest since World War II. The Swiss franc is sagging and the banking sector is losing its reputation as the world’s most secure.

People accustomed to job security and the comforting stability of cartels are facing layoffs and cutthroat competition. There is a nagging worry that the good times are ending.

Leading bankers and industrialists warn that Switzerland faces increasing competition from other European economies, and that it must reshape economic and political structures if it wants to remain prosperous.

Rainer Gut, head of CS Holding, one of the biggest Swiss financial services groups, said recently: “We have far too much of the feeling that we have a God-given right to the highest living standard in the world.”

How did a small, landlocked part of Europe with an underfed population become one of the world’s richest nations?

Most of the growth came after World War II, in which Switzerland was neutral.

Swiss export industries were able to meet demand that the exhausted and devastated economies of Europe could not. Fixed exchange rates and an undervalued franc made Swiss goods competitive.

Plentiful capital resources, lent at the lowest rates in Europe, honed the competitive edge of Swiss companies.

Discreet and secure Swiss banks became a haven for the savings of dictators, refugees and tax evaders. At times, the banks had so much cash they could charge depositors negative interest rates.

The influx of cheap foreign labor, mainly from Mediterranean countries, helped to keep wages stable.

And as Hansjoerg Siegenthaler, professor of economic history at Zurich University, said in an interview, Switzerland’s traditional system of political consensus also spared it from severe labor unrest.

While industrial relations in many other Western European countries were hit by radical politics in the 1960s and 1970s, in Switzerland “trade unions simply did not make excessive and exorbitant wage demands,” he said.

Recently, however, many of those advantages have evaporated.

The Swiss franc is no longer the currency of last resort.

Swiss banking has had to improve its image and the “numbered bank account” does not afford the privacy it once did. The banking sector’s reputation suffered a severe blow last year when a number of small and medium-sized banks were shut down.

Layoffs, once unheard of, have occurred throughout the economy; the bankruptcy rate rocketed.

The Swiss see the key to their future in European Community membership, but they can’t agree on whether this will maintain their standard of living.

The small entrepreneur is skeptical. Cartels abound in Switzerland, and many small companies fear losing the comfort of price-fixing that EC anti-cartel legislation and competition would entail.

Many Swiss also wonder whether they want to give up foreign policy neutrality, and an idiosyncratic political system that allows the electorate to veto government legislation, in exchange for a stake in the EC market.