Call of Duty: World at War shows the Radeon HD 5770 consistently outperforming the Radeon HD 4870 at all three tested resolutions. Specifically at 2560x1600 with 2xAA enabled, the new card averaged 36fps, making it about 12% slower than the GeForce GTX 260. That said, the Radeon HD 5770 was 3% faster than the 4870, and 24% faster than the previous-generation Radeon HD 4770.
When testing with Company of Heroes, the Radeon HD 5770 was able to provide playable frame rates and even matched the 44fps rendered by the GeForce GTX 260 at 2560x1600. It was slightly slower at 1920x1200 and 1680x1050, with margins varying between 5 and 6fps when using these resolutions.