Lim said U.S. equity returns in real terms have averaged 6 to 7 percent, and most likely for the next five to 10 years that will be 2 to 3 percent. The S&P 500 is basically flat on the year, after suffering a steep decline in January and February before reversing it in the last several weeks. The index was down 0.7 percent for 2015.
"The central banks in the last few years have brought future returns forward," he said.
"The problem is once that's done, what is there to look forward to — very little," he said. "They bought time for their economies to improve."
The economies of developed regions like Europe and Japan are still growing sluggishly.
"We are very much in the camp of saying you need supply-side reform," he said. That could mean tax reform, pension reform and labor reform.
"Around the world, we only see China, Mexico and India trying to do something to make a difference" for their countries, he said. "Just everyone else is really relying on their central banks."
Lim was speaking to a delegation from the Financial Women's Association of New York, visiting Singapore last week as part of its annual international trip.
GIC holds its long-term portfolio in six asset classes, which it views as funding sources, he said.
Sixty to 65 percent of its portfolio is in the equity asset class in developed markets, emerging markets and in private equity investments. GIC also invests in fixed income and real estate.
"The U.S. is 45 percent of our exposure — the biggest investment destination for us," he said. Bridgewater Associates has been an investment partner with GIC for more than 20 years, he noted.
GIC looks for long-term opportunities in the $1 billion to $3 billion range.
Lim said GIC owns over 1,000 U.S. listed companies in small positions.
Lim said GIC is constantly looking at new technologies, such as cloud computing, block chain, electronic cars, self-driving vehicles, machine learning and renewable energy. He said the U.S. is the largest source of innovation, but he is also looking at opportunities in Shenzhen, similar in spirit to Silicon Valley.
— Disclosure: CNBC's Patti Domm is a member of the board of the FWA.