Over the years, Priceline.com (NASDAQ:PCLN) has always found ways to keep up the growth. But with its second-quarter earnings report, signs now point to things slowing down, especially in Southern Europe and the U.K. As a result, Priceline’s high-flying stock is off about 16% in today’s trading, to around $570.

Actually, the online travel company’s current earnings report did have some good news. Excluding one-time items and share compensation, Priceline’s second-quarter earnings came to $7.85 a share, up from $5.49 in the same period a year ago. Revenues spiked by 20% to $1.33 billion. EPS clearly beat the consensus of $7.36 a share, though revenues fell just shy of the expected $1.35 billion.

So why are investors dumping the stock so violently? Well, the problem is the outlook. Priceline forecasts third-quarter earnings at $11.10 to $12.10 a share and revenue growth of 9% to 15%. The Street analysts were looking for $12.76 a share and revenue growth of 24%.

Through savvy acquisitions, Priceline has built a strong European business. Its low-price model has certainly been effective in gaining market share. But the strategy is facing headwinds as consumers start to put off travel purchases.

In fact, it’s far from clear how quickly this trend might end. Even though the European Union has taken great strides to restructure its sovereign debt and banking system, wide-scale austerity will be around for a while. In such an environment, it seems reasonable that demand for travel products will remain soft.

Unfortunately, Priceline faces other major issues For example, the strong U.S. dollar is putting pressure on revenues. At the same, the competitive environment is getting tougher, such as with players like Expedia (NASDAQ:EXPE), TripAdvisor (NASDAQ:TRIP) and Orbitz Worldwide (NYSE:OWW).

Now, for the long-haul, Priceline’s future does look bright, with much room for growth in international markets. And the company has a big head start — and perhaps the biggest opportunity — in Asia, where Priceline is expanding aggressively. The latest deal is a partnership with CTRIP.com International (NASDAQ:CTRP), which will provide a nice boost in China.

Still, for the next couple quarters, Priceline will probably experience some turbulence. So, investors should probably hold off on the stock for now.

Tom Taulli runs the InvestorPlace blog IPOPlaybook, a site dedicated to the hottest news and rumors about initial public offerings. He also is the author of “All About Short Selling” and “All About Commodities.” Follow him on Twitter at @ttaulli. As of this writing, he did not own a position in any of the aforementioned securities.