Verizon's FiOS Internet and Cablevision's Optimum Online were the top high-speed Internet service providers in terms of their ability to deliver data at speeds faster than advertised during peak traffic periods, the FCC said its Measuring Broadband America Report Thursday.

In a test the FCC conducted during April, Verizon's 15 Mbps FiOS Internet package averaged peak-period speeds of 19.39 Mbps, delivering 129 percent of its advertised speed, the FCC said. The telco slightly edged out Cablevision's 15 Mbps tier, which averaged 19.14 Mbps, or 128 percent of its advertised speed during peak periods.

But when you take the average of multiple tiers marketed by broadband ISPs, Verizon's FiOS product and Cablevision were tied, with each delivering 120 percent of their advertised speeds during peak periods in April, the FCC said.

Also performing well were Comcast, which delivered 103 percent of advertised speeds during peak periods, Charter Communications , which delivered 98 percent of advertised speeds, and Time Warner Cable, which delivered 96 percent of advertised speeds.

The FCC said Cox Communications delivered 95 percent of its advertised speed during peak periods in April, while CenturyLink delivered 89 percent and Frontier delivered 79 percent of advertised speeds.

Frontier  was the only major provider to see its performance decline in the last year. It had delivered 81 percent of advertised speeds during a similar test in 2011.

Cablevision posted the biggest improvement in performance compared to last year's report, when the FCC said it delivered 54 percent of advertised speeds during peak periods. The company has invested in its network infrastructure and revamped its management team since last year's report was issued.

"This report demonstrates our commitment to delivering more than 100 percent of the speeds we advertise to our broadband customers – over the entire day and during peak hours – in addition to free access to the nation's largest WiFi network and other valuable product features and enhancements," Cablevision VP of broadband product operations Amalia O'Sullivan said in a statement.

Verizon chief marketing officer Mike Ritter cheered the FCC report, and said that the company expects the recent launch of its FiOS Quantum broadband tiers, which offer speeds ranging from 50 Mbps to 300 Mbps, will be reflected in next year's report. "We expect excellent results when these groundbreaking, industry-leading speed offerings are included, as do our FiOS customers," Ritter said in a statement.