Since the release of Microsoft Flight Simulator 2020 we’ve put the PremiumBuilds test rig to work, analyzing the factors that have the most impact on performance in this sim. In this article, we’ll discuss what we’ve found and use the data to inform component recommendations – such as the CPU, GPU and memory – so that you can be sure of getting the best performance in Flight Simulator 2020.
GPU killer, CPU hater, or just plain badly coded?
There’s been a lot of talk about Flight Simulator 2020’s performance since its release, and not all of it has been positive. In particular, people have pointed to benchmarks and testing showing frame rates in the mid 40’s on high-end hardware – indeed the highest-end hardware, and claimed that the game is a dog, or that no PC can run it well. This is unfair. It’s perfectly possible to specify a system that runs this game fluidly and at acceptable frame rates. It’s a more involved process than for a ‘normal’ gaming PC though: there are interdependent factors at play and imbalances between components or incorrect settings can be detrimental to the experience. This article uses the data to help you understand exactly what makes this sim tick.
Simulators: They’re not just toys.
The first major issue is that whilst it can be achingly beautiful Flight Simulator 2020 is a simulator, not a game in the traditional sense. There is a complex flight model running behind the scenes, calculating the physics that dictate whether you’re flying or falling. Ultimately it is this physics model that constrains performance. Our testing shows that the game uses just 4 threads (and yet can still max out 8 core CPUs at times) and performance is primarily dependent on the single-core speed of the CPU.
That said, no current hardware will exceed around 60 FPS in this game using the full flight model. Frame rates are variable and we conducted our testing under the most challenging conditions because these place the biggest demands on the underpinning hardware. Where we’ve demonstrated a playable 35FPS over a busy city it translates to a buttery smooth 50 FPS+ flying high over less complex terrain on the same configuration. There are also still some consistency issues particularly as the sim initializes at a busy airport or when you overfly a complex urban area. You shouldn’t be surprised to see frame rates in the low teens in this situation but it smooths out after a few seconds. We experienced this across almost all configurations and have witnessed it in others testing too so it appears to be an ingrained issue with the code, not the hardware. Hopefully, such performance inconsistencies will be ironed out as the sim matures. In particular, it relies on the aging Direct X 11 API, one of the reasons it’s so constricted to 4 cores. There is a planned migration to DX12 in future and we’re hopeful this will bring substantial optimizations with it.
With those expectations set, let’s dig into the numbers and see what we can learn:
The testing protocol:
Every test in this article followed the same pattern. Using an A320 we took off from JFK Airport, climbing to 2000 feet, flying towards Manhattan and then turning left to overfly Manhattan before ending logging over the Statue of Liberty in a flight lasting 3 minutes. This is arguably a ‘worst case’ scenario for Flight Simulator 2020 with an airliner over a busy metropolitan area and many users have reported NYC ‘unplayable’. Each test was conducted in order to isolate the variable under test: For the CPU tests we ran an RTX 2080 Ti GPU at 1080p and high graphics settings ensuring that the system was entirely CPU bound throughout the flight. When testing GPUs we used our Ryzen 3600 test system with 16Gb RAM at 3600MHz. The Ryzen 3600 was chosen for two primary reasons: Firstly it’s more representative of the CPU that most people will be running. Secondly it demonstrated more consistency than the pure 8 core i7-9700K, probably because of the flexibility of the 6 physical and 6 additional logical cores made available via multithreading. Ram testing also used the Ryzen CPU owing to the known benefits of RAM speed with Zen 2 CPU’s but kept the GPU and game settings the same.
Flight Simulator 2020 CPU scaling
We can see in the graph above the impact of CPU performance, from a Ryzen 3100 analogue (in fact the Ryzen 3600 with 2 cores disabled) to the 6 core 12 thread Ryzen 3600, followed by the 8 core Intel i7-9700K in various states of overclock. The broad pattern is consistent with game performance closely tied to CPU performance but there are a couple of features of interest. Firstly note that the 4C/8T CPU suffers terrible performance in Low, 1% Low, and 0.1% low metrics: This is indicative of the playing experience with large and frequent stutters, lag and spikes. Despite this for the most part the game was playable with the aircraft controllable but it is far from ideal.
Contrast those results with the six-core, 12-threaded Ryzen 3600: Here we see a small increase in peak and average FPS, but a marked improvement in the Low and 1% Low metrics, from 10-12FPS to 26 and 20 FPS respectively. This manifests in a much more consistent playing experience with smooth framerates and little stutter. Note that the 0.1% lows remain in the basement, at 8 FPS: They will become a consistent feature of this analysis whenever a CPU limit is encountered.
Moving to the Intel i7-9700K, this chip has been on the podium of gaming CPU’s throughout 2019 and the first half of 2020 with only the i9-9900K and now the Comet Lake iterations superseding it. It marginally outperforms the Ryzen 3600 in Flight Simulator 2020 at stock speeds but still suffers from rock bottom 0.1% lows. Overclocking it to 4.7GHz and then 4.9GHz sees a small improvement proportional to the increased clock speed and importantly an improvement in 1% and 0.1% Lows – the CPU is being maxed out less often at this higher clock speed. This allows us to draw the conclusion that FS2020 peak performance is indeed dictated by the CPU, and primarily by the CPU’s individual core speed and not necessarily the total CPU performance.
Logging CPU usage throughout testing rarely saw any CPU exceed 60% utilization. However, logging on a per core basis sees individual cores hitting their limit at 95%+ utilization. Occasions where all active cores become swamped correlates to those instances of 0.1% Lows in frame rates. This is visible on the graph below: The dotted lines represent lesser used cores, the dashed lines the more prominently used cores that are running the game code. On two occasions here we see spikes towards total CPU utilization denoted by the solid red line. These instances correlate to several seconds of very low performance with long frame times and stutter and is the source of those shockingly low 0.1% lows when CPU limits are reached.
Simply put, when the CPU can’t cope with the game engine, it stalls and we see a huge spike in frame time as the GPU sits and waits for information to render the next frame. See videos of a Ryzen 3950X making just 44FPS in FS2020 whilst showing under 20% utilisation? Now you know why. This Sim cannot use more than 4 cores.
CPU Scaling Conclusions
Microsoft Flight Simulator needs a combination of adequate cores and the highest individual core speeds possible. The Ryzen 5 3600 performs admirably and would be our recommendation for anyone building on a budget. Mid-tier processor recommendations go to the Ryzen 7 3800X due to its 8c/16t topology and 4.5GHz boost speed, and the Intel Core i5-10600K due to its even higher single-core capability and hyperthreading. At the high end we recommend the Intel Core i7-10700K or the i9-10900K – and if you’re serious about squeezing every last frame out of Flight Simulator 2020 – then a strong cooling solution and some time spent overclocking is well-advised no matter what CPU you opt for.
Flight Simulator 2020 GPU Scaling – 1080p
Examining GPU performance in Flight Simulator 2020 allows us to further explore the relationship between GPU power and CPU capability. It is often said that this game needs a very powerful GPU to run well but that can actually lead to significant performance issues if the underlying mechanisms aren’t understood. This is a sim where turning your graphics settings up can actually improve performance!
In these tests we used the Ryzen 3600, 16b of Ram at 3600Mhz CL15, and the GPUs as described without overclock. We ran the game at 1080p, High settings with photogrammetry on. We flew our standard flight path over NYC and logged the data.
These results may look counter-intuitive at first but consider them in context of the CPU performance limits we discovered in the section above.
The GTX 1660 Super performs well here with acceptable average frame rates and importantly for the playing experience relatively high 1% and 01.% lows. Of all the testing done these runs stood out as the most fluid. The secret? This set up is completely GPU bound. The GPU utilization sits at 95% or above, showing that it’s the GPU and not the CPU and thus game engine that is limiting the speed of the simulation. This results in smooth consistent frame rates.
Moving to the EVGA RTX 2060 KO, a significantly more powerful GPU we see an increase in average and maximum frame rates but this is at the expense of the 1% lows and particularly the 0.1% lows which are sub 10FPS. This is embodied in gameplay as noticeable stutters and hangs that were not present when using the GTX 1660 Super.
The trend continues as we step up to the big guns. Both the GTX 1080 Ti and RTX 2080 Ti show very low 0.1% rates of just 1 and 8 FPS respectively. So what is happening here?
It comes down to the trade-off between CPU and GPU performance. Both the GTX 1080 Ti and RTX 2080 Ti are criminally underutilized at 1080p and this means that the CPU is working flat out and frequently hits peak capacity. The GPU is left waiting for data and the result is a frustrating and jerky experience at times. Note that despite the prodigious rendering power of the RTX 2080 Ti we cannot exceed the ultimate performance limiter: the CPU. When that happens it results in lag, stutter and an ugly playing experience.
Flight Simulator 2020 GPU Scaling -1440p
Here we’ve moved up to 1440p resolution which is a common resolution in Sim rigs owing to the need for an increased level of detail to view cockpit instrumentation. Of course, the virtual world build by Asobo comes alive at this resolution too, and the demands on the graphics processor increase greatly.
The GTX 1660 Super struggles at 1440p. We don’t approach a CPU limit with utilization around 40%. The poor minimum, 1% Low and 0.1% low framerates are all the result of a GPU that’s incapable of keeping up. Stepping up to the RTX 2060 KO we see it come into its element at this resolution and settings, allowing the CPU to be near fully utilized but never smacking off of the performance ceiling and inducing stutters. This can be seen in the healthy 1% and 0.1% low numbers. This GPU gave slick playable results at these settings with a Ryzen 3600 much as the GTX 1660 Super excelled at 1080p high settings.
Moving up to top tier GPUs again does little for performance: in fact it hurts the low end a little as we encounter occasional CPU limitations which bring smooth play to a halt. The RTX 2080 Ti sees the highest average and high FPS rates at 50 FPS and 60.7 FPS respectively but drops 0.1% lows to 13.3 FPS versus the RTX 2060 KO’s 17.8FPS in that metric. It still provides a smooth and playable experience but we actually benefit from a move up to ultra settings here, increasing the load and smoothing the framerate.
These results highlight the delicate balance that needs to be struck when selecting a GPU for Flight Simulator 2020. You need to be sure of your target resolution and settings as well as the performance limitations of your CPU prior to deciding on the best GPU. The saving grace here, of course, is that settings can be tweaked to perfectly balance GPU load and take the heat off of the CPU. So as long as your GPU is in the correct performance bracket you can fine-tune it to your taste and to eliminate CPU bound situations.
Our GPU Recommendations for Flight Simulator
To conclude the GPU testing section here are our GPU Recommendations for Flight Simulator 2020:
- 1080P – The GTX 1660 Super provides excellent performance at 1080p high, whilst the Radeon RX 5600XT and RTX 2060 will perform well at Ultra settings. GPUs with more performance than this may actually induce worse playability unless you have a top tier CPU to support them.
- 1440p – We recommend an RTX 2060 Super, RTX 2070 Super, or the Radeon RX 5700XT for best performance and the ability to enjoy this sim at high or ultra settings.
- 1440P Ultrawide: An RTX 2080 Super or RTX 2080 Ti provide excellent performance at this resolution on Ultra settings.
- 4K: At 4K an RTX 2080 Super, RTX 2080 Ti, or one of the new Ampere GPUS is required for adequate performance on high settings.
Flight Simulator 2020 Ryzen RAM Scaling – Speed and capacity
AMD’s Ryzen processors have always been sensitive to RAM speed. The most recent Zen 2 parts are no exception and we’ve demonstrated how performance scales with optimally selected RAM.
In these tests we ran the system at 1080p with the RTX 2080 Ti to isolate CPU performance.
Worst case scenario is ‘default’ JDEC speeds of 2133 MHz. We can see this costing 10FPS or nearly 20% on average and maximum frame rates. 2666 MHz CL16 performs acceptably well is around 5 FPS or 10% down on better-optimized RAM. From 3000 MHz CL14 to 3600MHz CL14 speeds are less critical although 3600MHz posts the fastest average and maximum frame rates, it loses out to the 3000 Mhz ram in Minimum and 1% lows. It’s not clear exactly what causes this from the testing we’ve conducted but the results are on par across the higher speeds from 3000MHz to 3600MHz.
The overall trend here is a useful analogue for the general point about the importance of CPU core speed in Flight Simulator 2020. You certainly need optimized ram to allow the CPU to perform to its potential and be sure to enable the RAM speed profile in BIOS!
16GB vs 32GB RAM for Flight Simulator
We tested three RAM configurations as Microsoft recommend 32GB for Flight Simulator 2020. We ran tests of 32GB 3000MHz CL15 ram in 2x16GB dual-channel mode against 2x8GB at the same speed. We also tested a single 16GB stick, necessitating single-channel operation.
There was no discernable performance difference between the two capacities, in fact 16Gb slightly out performed 32GB but not beyond margin of error. Interestingly when 16Gb was installed utilization hovered between 12 and 14GB, whilst with 32GB installed utilization reported between 16.5GB and 18.5GB: The game clearly can use more ram perhaps for pre fetching assets or textures but there doesn’t appear to be a huge difference in performance. The single channel 16Gb stick performed worst as expected nearly 10% behind the dual channel configurations. With ram prices dropping it seems sensible to buy a 32GB kit for this sim if the budget allows, but if it comes to a choice between 32GB RAM or a better CPU or GPU, we’d take the upgraded core components and 16GB. 32Gb will be required if you intend on doing any form of multitasking whilst running the simulator.
RAM Recommendations for Flight Simulator
For Ryzen 3600Mhz CL16 RAM is optimal (see our upcoming Ryzen RAM performance analysis article), and Flight Simulator 2020 is no exception. If you’re on a budget 16Gb doesn’t appear to hurt performance at all, but 32GB adheres to the developers recommendations and may prove sensible. We’d certainly recommend 32GB if you intend on expanding the game with modifications and additional assets, or running on a high-end CPU and GPU combination. To partner an Intel CPU, we’d recommend 3000MHz CL15 or faster RAM in a 2x16Gb kit.
Conclusion: Building the best PC for MS Flight Simulator 2020
In order of importance the factors that enable good performance in Flight Simulator 2020 are:
- A high-performance CPU with at least 6 and preferably 8 cores and multithreading.
- A current-generation GPU capable of good performance specific to the target resolution.
- Ideally 32Gb of speed optimized RAM in dual channel mode.
- An SSD – for load times rather than outright performance
Critically, the CPU and GPU must be carefully balanced to work in harmony. The CPU dictates the ultimate performance ceiling of the simulator whilst the GPU must be capable of matching the framerate at the desired settings. If you’re experiencing ugly stutters, you may find that increasing your graphics settings cures them! Alternatively, the 20, 30 and 60fps frame rate caps can artificially limit frame rates to give the CPU breathing space. If all else fails we’d suggest experimenting with those settings. You may have to sacrifice average frame rates for consistent frame times.
Ultimately Flight Simulator 2020 is a simulator that will tax the highest-end hardware currently available at high settings and resolution, but it will also run very well on mid-range equipment. To label it as poorly coded or unplayable is grossly unfair. Our extensive testing shows that with the sweet spot of hardware you will enjoy fluid, immersive play with utterly bewitching graphics and the full flight simulator experience. It needn’t cost the earth to be able to fly the world.
