It's easy to understand the appeal of Unity. It's simple to prototype a new game concept, the tools are very friendly, and there's a vibrant community out there to tap into. It seems like a great place to build a game. However, as things stand, the way Unity handles certain tasks isn't always optimal. In its current iteration, console developers familiar with the tech tell us that the engine struggles with proper threading, which is very important on a multi-core platform like PlayStation 4.
This refers to the engine's ability to exploit multiple streams of instructions simultaneously. Given the relative lack of power in each of the PS4's CPU cores, this is crucial to obtaining smooth performance. We understand that there are also issues with garbage collection, which is responsible for moving data into and out of memory - something that can also lead to stuttering. When your game concept starts to increase in complexity the things Unity handles automatically may not be sufficient when resources are limited.
Games built in Unity have a long history of suffering from performance issues. Unstable frame-rates, loading issues, hitching, and more plague a huge range of titles. Console games are most often impacted but PC games can often suffer as well. Games such as Galak-Z, Roundabout, The Adventures of Pip, and more operate with an inherent stutter that results in scrolling motion that feels less fluid than it should. In other cases, games such as Grow Home, Oddworld: New 'n' Tasty on PS4, and The Last Tinker operate at highly variable levels of performance that can impact playability. It's reached a point where Unity games which do run well on consoles, such as Ori and the Blind Forest or Counter Spy, are a rare breed.
There is some hope on the horizon, however - the latest update of Unity, version 5.4, is scheduled for March 16th. We're told that this will include a number of performance enhancements including better threading - something very useful for CPU-limited consoles. Members of Campo Santo, the game's developer, have already posted a number of tweets suggesting that these improvements are in the works for Firewatch.
