Meanwhile on Xbox...
Game just works;
May or may not be an accurate explanation as I am not a programmer but I'll post it here.
Game Revolution reports:
"Until now the issues have been blamed on lack of optimization, especially after thousands of reports of consumers with GTX 1070's and other newer cards experiencing the issues first-hand. A recent major update was intended to address the problems by improving optimization, but had very poor results.
Thankfully, investigation by a user named
Rockstonicko on the official
Forza forums resulted in a possible explanation. The description of his findings included hardware utilization measurements in addition to bad news for PC gamers, as follows:
CPU usage: 15-29% (relatively normal)
GPU usage: 99-100% (also normal)
Used System Memory: 7983GB (4,258MB used by Forza process)
Dynamic Video Memory Usage: 4,365MB (take note GPU and CPU memory equal roughly 8GB, which is how much RAM XB1 has)
GPU MC Utilization: 0-15% (at 2560x1440 this should be in the 50-70% range, something is very wrong here)
GPU Power draw: 125-180W (in other games it's not uncommon to see 220w-310w, again, something is wrong)
So from this I can conclude the engine is still using similar memory management as is used on the XB1. When the GPU frame buffer is overloaded the game begins using system RAM as additional frame buffer memory. This also explains why people are seeing high utilization on 1 CPU core while the rest remain relatively idle.
On the XB1 the system RAM is unified, meaning video and system RAM are both accessing DDR3 RAM with 68.3GB/s bandwidth along with an additional bi-directional 50GB/s from ESRAM. Only massively overclocked DDR4 barely has the bandwidth to provide a smooth framerate when it's being used as additional frame buffer memory alongside GPU GDDR5. THIS CANNOT WORK WELL ON PC HARDWARE.
Put simply, it appears that the PC version was ported directly over from the Xbox One version.
The Xbox One's architecture uses a single 8GB chunk of memory as both system and video memory, allowing the frame buffer to be stored and handled in a single place. PC architecture is different with several memory locations (i.e. video memory, system memory, etc.) that can be used by developers when desired. Unfortunately, only video memory and the fastest DDR4 available really have the bandwidth necessary to be proper locations for a frame buffer in graphically intensive modern games. Secondary areas, like system memory, are sub-optimal.
It appears that
Forza Horizon 3's PC version uses these secondary locations of memory. This results in performance issues that impact the user experience.
This is a complex issue that likely has roots across large segments of code. Any fix will take time to produce, if there is ever going to be one."