FPS - the hunt for optimum performance

Discussion in 'Technical & Support' started by justposted, Oct 27, 2020.

  1. justposted

    justposted Registered

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    TL;DR In order to maximise performance, start by reducing texture quality until it fits within your VRAM. Keep number of opponents and number of visible vehicles drawn the same, then reduce that number as necessary to fit within VRAM. Drive at midday. Pause at the start of races until FPS settles.

    Long version ...

    Introduction

    Having bought the Nurburgring track yesterday I have been experimenting with settings to get the best out of my PC. I've had everything on maximum up to this point, but was seeing FPS as low as 20 on Nurburgring Endurance so obviously had to make some changes. After dozens of changes and test runs, this is what I have found. I can't judge whether my findings are universal or specific to my system, so would be interested to hear what others find.

    My System
    I have a 1070Ti with 8GB VRAM, a Ryzen 3600 6 Core / 12 Thread CPU and 32GB RAM. rFactor runs off an NVME drive. I run 2560x1080, so not super high or VR resolution. I'm also happy with a fairly consistent >40FPS and nice graphics, rather than reaching for 60-120 which some people prefer.

    My FPS figures are based on eyeing in FRAPS readings, which are typically lower at the start of a race, then increase and become more steady after the first 30 seconds or so. RAM for rFactor is read off Task Manager. VRAM and CPU usage figures are taken from HWiNFO.

    RAM
    Typically RAM usage (for rFactor only) sits at <9GB. The RAM usage only seems to increase above 9GB if I push over the VRAM limit, so I assume that it offload VRAM to RAM, which I think I've read elsewhere on this forum. It also means that 16GB RAM is probably enough in most situations, but once you start pushing your VRAM limits you might wish you had 32GB RAM to buy yourself some headroom with a bearable FPS hit.

    AI
    If I have more AI than I have set as the maximum number of visible vehicles, then I can see a FPS drop when a bunch of cars overtake me. Like 60FPS might drop to 25. So I assume that is where RAM data is being fed into VRAM. If I sit in position, then after maybe 15 seconds the FPS recovers suddenly.

    My conclusion is that it is best to only race as many AI/opponents as you can load into VRAM at once, otherwise you will see FPS drops when new cars go past. Not an issue in normal racing, but becomes one if you go off the track or pass a lot of people, when your FPS will dip for a significant time. The giveaway is RAM, so if you see RAM usage above 9GB once the track has loaded, then the chances are that you have exceeded your VRAM limit.

    CPU
    At the extreme, such as if I push to 60AI at Nurburgring, then I can see RAM up as high as 18GB and CPU at 35%. But generally CPU sits at 25% pretty much whatever I do. I have a 6C/12T system, so 25% is 1.5 cores or, more likely, one core with both threads maxed. In practice the load is spread across cores/threads.

    Loading Time
    Loading in cars appears to take some time. At the start of a race, if cars are a significant load (e.g. 30 cars at Nurburgring) then I press Pause at the start of the race. After a few seconds the cars are loaded in, presumably, as my FPS will increase from maybe 30 up to 45.

    VRAM
    Biggest reduction in VRAM requirement is from texture quality, so drop that until you are within VRAM limits. From Full to High at Nurburgring I can't see the difference, visually, but it sneaks me under the VRAM limit.

    Cars can make a difference. Older models might drop VRAM usage by 15% (Ferrari 488 vs Spark F3). Newer models have a less significant impact, like <5% between models. Some models seem to be easier to render, so you might gain 5-10FPS (Ferrari 488 vs Radical SR3-XX).

    8GB VRAM seems to be the sweet spot at 1080p. Nurburging with 30AI using recent car models just about fits in. You can certainly run with much less (until recently I had a 1060 3GB though didn't have Nurburgring), but there is a FPS hit from loading in track (?) and cars during the race.

    Time of day
    Even with cars that don't have headlights, FPS at midday can be 10-20 more than the same track at 6am, e.g. McLaren MP4/8 Nurburgring (60FPS -> 80FPS), though no impact on RAM/VRAM. Unreliable though. Makes no difference with many track/car combinations.

    Other quality adjustments
    Once you are within VRAM limits, other elements will affect your performance. But reducing things like number of AI or texture quality after that makes little difference to FPS. So consider running with no AI and on a small track, to eliminate those as sources of low FPS. Then experiment with other settings to see where you get the most impact.

    Big moves are worth about 5-10FPS each (taking them from max to min): shadows, circuit+player+opponent detail together, road reflection, environment reflection, 10AI. So from max everything to min everything is worth 30-40FPS and 20% VRAM. Texture max-min is worth 15% VRAM and no FPS change.

    The Auto-Detail FPS setting is supposed to reduce quality to hit a FPS target. I had little, if any, success with it. Better to manually play with settings, as described above.
     
    Last edited: Oct 27, 2020
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  2. stonec

    stonec Registered

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    Nice observations. I think we need to have some better way in the software to tell when resources like RAM or VRAM have been exceeded, or at minimum, have the sim pre-configure graphic settings in such a way that you get the best compromise between graphics performance and quality.

    Ideally you would have assets streamed live from SSD to RAM and RAM to VRAM the same way as all future console generation games will do, but current sims work with the idea of storing everything into VRAM at once, which makes them very dependent on the amount of VRAM. This makes it tricky because GPU manufacturers like Nvidia seem unwilling to put much more than 8 GB in their cards, so the average user will be stuck in this range of VRAM for the foreseeable future.
     
  3. Mitch9

    Mitch9 Registered

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  4. Paulus_NL

    Paulus_NL Registered

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    Got some big fps issues when racing during sunset/night etc.
    During the day (12pm etc) i get some got fps and sometimes hitting the 120fps.
    But as soon the lights go on or the sun is going down it can drop to 40 or 38 at some points. And going from 120 to 40 in front of taking a corner sucks :p Also time multiplier enabled/disabled doesnt make a difference. Lowering settings doesnt give a big fps boost or stable fps.
    Racing with 19 or 59 AI (Le mans) doenst give a big improvement. Lowering max visible cars isn't realy helping.

    Its on official S397 tracks like le mans, nordschleife etc. But also on non official tracks like Spa (which isnt using the new shaders etc).

    Running on a i7-7700K 4,7ghz, msi 1080ti, 16gb ram.

    Still trying to find a good setting so i can enjoy some endurance (offline) again.
     
  5. justposted

    justposted Registered

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  6. justposted

    justposted Registered

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    That's disappointing. I wonder what it is. All I can think of is RAM, as you could be hitting 16GB depending on how your system is set up, so at that point I can imagine sudden FPS hits as something gets loaded in. I'll try comparing RAM with/without lights and report back. [Edit: nope, the RAM usage on my machine is the same for day and night]

    Maybe you could try running without any opponents, so that at least you know whether that is a factor in the frame drops.
     
    Last edited: Oct 27, 2020
  7. Paulus_NL

    Paulus_NL Registered

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    RAM is around 10 or 11GB during the race. Also no change in that value in a day or night race.
     

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