Xbox One Vs. PS4: ‘Assassin’s Creed: Unity’ CPU Bound And Slower On The PlayStation 4?

The PS4 Vs. Xbox One wars continue to this day, and PlayStation 4 fans have been quite dismayed to find Assassin’s Creed: Unity CPU-bound, making it noticeably slower in regards to frame rate. But if the PS4 GPU is so much faster then how could this happen?

In a related report by The Inquisitr, Ubisoft is hurrying to pull together an Assassin’s Creed: Unity patch in order to fix all “horrifyingly hilarious” glitches that can happen in-game. When Microsoft dropped the Xbox One price, it seemed to shift the balance in the Xbox One Vs. PS4 war because now PS4 sales have actually been eclipsed in North America.

PC gamers realized something was up when they launched their high-powered gaming rigs and realized they were “only” getting frame rates in the range of 40 to 60 fps, depending on the system configuration. Most of the complaints come when the gamer is wading through the noticeably thickened crowds of the new Assassin’s Creed.

According to a video released by Digital Foundry, despite both the Xbox One and PS4 running at the same 1600 x 900 resolution, the Xbox One typically is leading by about five frames per second when gamers wade past dozens of NPCs or while free-running across the rooftops. This results in a barely tolerable 25 to 30 frames per second on the Xbox One, while on PlayStation 4 the frame rate often dips down into the teens.

When Ubisoft was asked to explain the low performance on the next generation platforms, they called Assassin’s Creed: Unity CPU-bound.

“We decided to lock them at the same specs to avoid all the debates and stuff,” Unity producer Vincent Pontbriand told Videogamer. “Technically we’re CPU-bound. The GPUs are really powerful, obviously the graphics look pretty good, but it’s the CPU [that] has to process the AI, the number of NPCs we have on screen, all these systems running in parallel. We were quickly bottlenecked by that and it was a bit frustrating, because we thought that this was going to be a ten-fold improvement over everything AI-wise, and we realised it was going to be pretty hard. It’s not the number of polygons that affect the frame-rate. We could be running at 100fps if it was just graphics, but because of AI, we’re still limited to 30 frames per second.”

But why is the Xbox One so much faster? Microsoft made the last-minute decision to bump the Xbox One CPU up to 1.75 GHz, while Sony kept the PS4 CPU at the original 1.6 GHz design. But that’s less than a 10 percent difference. The Xbox One ESRAM should not be an issue in this case because the design has the 32 MB of on-die memory dedicated to the GPU, and Microsoft has previously said they did not build in a way for the CPU to access the ESRAM.

Otherwise, both of the AMD-produced processors are very similar to each other design, except for the memory architecture. The Xbox One went with lower bandwidth DDR-3 memory while the PS4 memory is GDDR-5, but Microsoft gives developers access to 5 GB of memory while Sony limits games to “only” 4.5 GB. This might be an issue since PC testing has shown that Unity can use around 3.5 GB in video memory and up to around 2.3 GB in system memory (keep in mind that, unlike PC gaming systems, consoles have shared memory pools for CPU, GPU, etc.).

The other major factor is the rendering API (Application Programming Interface). Due to the game design of Assassin’s Creed: Unity, there’s a huge number of draw calls for all of the objects you see on screen. This means the PS4 CPU is working hard to prepare the draw call data for the PS4 GPU, which can create yet another CPU bottleneck for performance. It’s possible the PS4 API is simply not as optimized for these type of gaming scenarios since most of the time modern video games tend to be GPU-bottlenecked.

If this is true, it almost makes you wonder what the Xbox One DirectX 12 update could have done for the Assassin’s Creed: Unity Xbox One version. It also should make gamers wonder if the PS4 GPU is idling enough that it could have handled the full 1080p experience.