Cities: Skylines II is the slowest game we've tested this year. Playable frame rates are out of reach even with the most expensive GPUs. In 4K, even the powerful GeForce RTX 4090 does not reach 30 FPS, while the Radeon RX 7900 XTX struggles with an average of less than 17 FPS. The others strive to maintain double-digit averages.
We tested Cities: Skylines II with a Core i9-13900K on an ASUS ROG Maximus Z790 Hero motherboard. The system was associated with a 32 GB QC memory clocked at 6000MT/s and a Corsair RM1000E. The CPU was cooled using a Lian Li Galahad 360 AIO liquid cooler.
At 4K, it's pure carnage, even for the fastest GPUs on the planet. The GeForce RTX 4090 barely manages to cross the 20 FPS mark with minimums of 8 FPS. AMD's RDNA 3 flagship, the Radeon RX 7900 XTX, is good for 17 FPS with lows of only 5 FPS. The RX 7900 XT makes do with 14 FPS with a 1% low average of 4.5 FPS. The GeForce RTX 3080 Ti is a bit slower, averaging 13 FPS.
From the gaming time graph, it is clear that none of the GPUs provide a playable experience. However, the RTX 3080 Ti and RX 7900 XT are particularly static, with peaks of over 400 ms. Interestingly, the gaming time variance graph shows that the RTX 3080 Ti is smoother overall than the RX 7900 series.
At 1440p, the fastest Radeon and GeForce cards exceed the 30 FPS mark with minimums of 17 and 15 for the RTX 4090 and the RX 7900 XTX. The Radeon RX 7900 XT achieves 25 FPS, while the RTX 3080 Ti achieves 23 FPS on average. Once again, the bass is higher for the RX 3080 Ti than for the RX 7900 XTX.
Radeon cards continue to struggle at 1440p, with several frametime spikes over 100ms. The GeForce RTX 4090 is the smoothest, followed by the RTX 3080 Ti.
At 1080p, most modern GPUs should offer playable frame rates. Cities 2: Skylines is an exception. Both the RTX 4090 and RX 7900 XTX average over 40 FPS with minimums of over 20 FPS. The RX 7900 XT and its rival Ampere cross the 30 FPS threshold but are limited to rates below single digits.
Frame time variance is a repeat of the first two tests, with the GeForce RTX 4090 finishing first and the Radeon RX 7900 XT finishing last.
Cities II: Skylines is a huge city simulator, and titles of this type tend to be CPU intensive. However, it is so poorly optimized that the GPU is continually stressed, leaving the CPU with a lot of room to maneuver. Below you can see the GPU usage times at 1080p with an RTX 3080 Ti and an RTX 4090.
RTX 3080 Ti
RTX 4090