FPS Drops in Rain

[SchmockLord]

Hi guys,

I have played AC, PCARS2, iRacing and now begin to like rFactor 2.

Overall It looks good and runs smooth, even on high settings.

But I have noticed, that the fps drop from 90 to 45 fps whenever I start in rain and only in the starting grid up to the first couple of turns.

First I thought the drops come because of the number of details on the track around the starting area and because of the number of cars to render around me.

But after a couple of races, I realized, that this only happens in the first round and only the first couple of turns. Even when the grid stays the same, the drops don't occur from the second lap on. From the second lap on I get 90fps steady and <5ms frame times.

Also, the drops not really change no matter how high my graphics settings are. It seems to be a bug or something.

Does anybody know the reason for this and observed the same?

I play it VR only on my Quest 2.

I have a very powerful PC: 10900k, 32GB, 3090.

Settings in rFactor:
SteamVR SS: 170%
FSAA: 2
Post Production: High
All other settings: High

 

[Martin Vindis]

Rain spray is the culprit, it's badly optimized and even if you reduce visible vehicles the spray is still rendered.

 

[Shovas]

It may also be reflections (from surfaces like car body, road, etc.). I've recently been in the habit of turning down or off reflections in sims as honestly it's not that much of a loss and the FPS win tends to make it worth it.

 

[davehenrie]

I have even gone so far as to disable the rain drops. This gives my old old R480x8 the ability to perform at 140fps with a 19x12 screen. I think having freesync helps but even with that performance, rain and especially rain at the sundown-sunset time periods really put a strain on rF2 graphics. If I were competing in a league, I'd probably enable the rain drops and bite the bullet on fps.

 

[Case_]

(BTW, unless something changed lately, disabling rain drops improves performance even in dry weather with no rain.)

 

[John-Eric Saxén]

Doesn't the FPS drop automatically to 45 when it goes under 90 in VR? In other words, it may be that your actual FPS for example is 105 in dry and 80 in wet, but you get 45 as it has to halve the nominal refresh rate.

If a game is optimized properly, rain will cause quite a bit FPS drop simply because more effects to render equals less performance. Having said that, rF2 is one of the worse ones on that front. My guess is that the frame drops are mostly caused by rain drops rendered on your opponents cars and once the field spreads out on lap two, it no longer has to render so many of those.

As others suggested above, turning off rain drops is probably the most obvious way to improve the performance.

 

[MarcG]

If you're racing AI in the Rain they stick their Headlights on, so the multiple Dynamic Lights will also suck performance down (just as they do at night) .

 

[SchmockLord]

Thank you, guys. Regarding the drops to 45 whenever it cannot reach 90: Yes, I know that.

But the framerates are between 45 and 90, e.g. 56, 61 etc.

But playing longer it seems to be pretty random when this happens. Sometimes only at night, sometimes at day. But mostly during rain.

I will try to disable the raindrops, but this kind of eliminates the purpose of driving in rain, because everything looks so cool

 

[SchmockLord]

So I have done more testing.

Nordschleife. Rain. Daylight 4pm. 12 opponents.

Disabled ASW so I can see the real FPS rendered.

Tested first with High settings then turned off almost every effect: Shadows, Rain, Reflections etc.

Attached are both settings.

In both scenarios, the behavior was the same:
In the starting grid 44 to 51 fps. 20ms frametimes (orange). After 3 or 4 turns it instantly goes up to 90fps and 9-10ms (green) and stays there until the end of the race.
I just hold my position after start and the grid was the same after 3 to 4 turns.

No matter if all settings were high or off.

And this to me is an indication, that this has almost nothing to do with the settings.

But I can live with that, now that I know I cannot really change this and it only happens at the start. And even if it happens, ASW steps in and gives me 90fps on the Quest

High Settings

Low settings

 

[fleezy]

hey schmock your issue might be more closely related to oculus and steamvr compatability, but i would start by checking to make sure that if you are using steamVR RR170% that you arent also using any render supersampling in the oculus app. if you are, you are rendering at 1.7x whatever your oculus app is, which may be increasing your res beyond what you expect.

if your not, u might just want to drop your RR down a little bit, lol

if you're launching in CM, there is an oculus pixel per display counter i would use instead.

if you're using oculus link or airlink, you should make sure that oculus is your openXR runtime, not steam and turn off ASW in the Oculus Debug Tool. if you're using VD, i don't think it matters.

also consider tuning on AMDs FSR in CSP > Graphics Adjustments. It works with nvidia cards despite being AMD

 

[Rebel_488]

hey schmock your issue might be more closely related to oculus and steamvr compatability, but i would start by checking to make sure that if you are using steamVR RR170% that you arent also using any render supersampling in the oculus app. if you are, you are rendering at 1.7x whatever your oculus app is, which may be increasing your res beyond what you expect.

if your not, u might just want to drop your RR down a little bit, lol

if you're launching in CM, there is an oculus pixel per display counter i would use instead.

if you're using oculus link or airlink, you should make sure that oculus is your openXR runtime, not steam. if you're using VD, i don't think it matters.

also consider tuning on AMDs FSR in CSP > Graphics Adjustments. It works with nvidia cards despite being AMD

Cm, csp? This is rf2

 

[fleezy]

Cm, csp? This is rf2

LOL! so it is... i crossed out what wasn't relevant, the rest it.