There is evidence that the rapid rate of growth might not be sustainable and that the economy has vulnerabilities.

Growth in Poland’s G.D.P., which remained robust in the first years of the financial crisis — 4.5 percent in 2011, for instance, according to the World Bank — slowed the last two years, to 1.9 percent in 2012 and 1.6 percent last year. The government’s budget deficit is at worrisome levels and consumer spending, which fueled the Polish economy early in the crisis, has begun to slacken.

But even with its limits, the strength of the Polish economy has helped give the country additional credibility and influence in Europe, especially as other countries, like France, Spain and Italy, have stumbled. The most recent evidence for this was the election of Donald Tusk, Poland’s prime minister, as president of the European Council, the first leader from a former Soviet bloc nation to hold such a top-level position.

“It is a source of great satisfaction that our voice is better heard and the Polish prominence in European politics is growing,” President Bronislaw Komorowski said in an interview.

Poland, with more than 38 million citizens, is by far the most populous of the former Soviet satellite states; four times the size of the Czech Republic, for instance. And it has by far the largest economy in the region.

Stanislaw Gomulka, a lecturer for 35 years at the London School of Economics and a longtime adviser to the Polish government, was one of the economists who shaped the “shock therapy” that transformed the Polish economy after the collapse of the Soviet Union and laid the groundwork for the current prosperity. He says those early reforms played a major role in Poland’s economic vitality, as did the auspicious arrival of a gush of European Union aid — so far about 139 billion euros, or $180 billion, with an additional 106 billion euros, or $138 billion, set to land by 2020.

“The E.U. money became available in May of 2005, but it took about three years to produce suitable projects on which to spend it, so the investment started to hit the economy just as the financial crisis was happening,” Mr. Gomulka said. “That’s where the luck comes in.”