when I play anything that isn’t Rio my game works fine buttery Smooth but for some reason Rio has extremely unplayable lag which makes it hard to even finish the race 
Here are my system specs:
Laptop: ASUS RoG G752VT-DH72
CPU: Intel Core i7-6700HQ 2.6GHz (Turbo up to 3.5GHz)
RAM: 16GB DDR4 (2133MHZ)
Storage: 1TB 7200RPM + 128GB SSD
GPU: NVIDIA GTX970M 3GB GDDR5
I have noticed this as well. What’s odd about it is my GPU never exceeds 83% usage, even though I get horrible lag. Could it be a CPU bottleneck?
My setup;
Intel 4770K
GTX 970
16GB DDR3
Samsung 850 Evo SSD
Turns out restarting the game fixes it, pretty odd if you ask me.
So yea if the game starts lagging uncontrollably just close and re-open the game and it should be fine
My machine is a bit older, but should handle this game. Even at lower resolution and no AI controlled opponents I still get lag.
Specs:
i5-2600k
2GB 670GTX
8GB DDR3 @1866Mhz
WD Velociraptor HDD @10000RPM (game install)
Having the same issues, every track from Rio has some crazy frame lag, but every other race be it raining, shine, or night, they run efficiently without any hiccups. Restarting the game, or even my computer doesn’t seem to fix this. I think it’s an optimization problem.
My specs:
i7-6700k @ 4.4ghz
MSI Z170A PC MATE
16GB 2400mhz DDR4 Corsair Vengeance LPX
EVGA GTX 970 SC
SSD 128GB Crucial
Corsair CX600M
I’ve got a similar machine to yours and Rio runs perfectly, I found that setting the settings higher, like Ultra actually makes the game run better and smoother, go figure.
My specs
i7-6700k @ 4ghz
16GB 3200ghz DDR4
Gigabyte GTX 960 OC DDR5
SSD 120 AND 240
Confirming heavy lag and framerate drops in Rio aswell.
Even on other Tracks i get random lagspikes, well, more like freezes. Game hangs up for a few seconds and then continues normally.
Asus Strix R9 390
i5-4590
ASRock Z87-pro3
What I have noticed when the lag starts is that the HD light is constantly lit up as if the game is doing very heavy swapping even though I got 16gigs of ram…
Lag confirmed. 16 GB RAM
Yeah, there’s definitely an issue with the optimisation on this track. Without being able to open the model files and texture files I can’t check properly what the source is though.
Lag spikes also confirmed on other tracks, most noticeably on Spa in rain - that’s where it’s occurred most for me.
Interestingly the lighting on Rio looks much worse than any other tracks, the game definitely looks uglier there because of it. Especially noticeable on lower settings.
Specs:
AMD A10-6800K 4.1GHz
ASUS GeForce GTX 750 Ti 2GB
12GB RAM
500GB SSD
Chiming in here, I get small lag spikes only on Rio and occasionally on Yas Marina. They’re quick but noticeable, a frame missed at 130MPH is kind of a big deal.
Specs
3770k @ 4.6 GHz
R9 290x
16GB RAM
Samsung 840 SSD
It is not so much the track I think but more how long you play. The lag starts to creep in after a few races and rebooting the game will magically fix it for a while.
Absolutely. The only way I could get this map to run well, was to use the practice mode first. Even after restarting the game, the lag continues.
That weird framerate bug happens for me too sometimes. Yesterday it was capped at 43fps. I restarted the game and the fps was back to 85.
Thank you for taking the time to report your issues. We will pass the information along.
I have the same problem.
on the 6 career race in rio, the game lags very badly and it makes it unplayable. I have no problems in the earlier career races or other single play races. I even tried changing the graphic settings between low/medium/high and it didnt help
What is about this career mode or track that makes the game do this?
My desktop has the following specs:
CPU:AMD FX-6350
16GB of Ram
GPU: NVIDIA GeForce GTX 750 Ti FTW
HDD: Samsung 850 Pro
I can confirm really bad lag on the Rio track as well. No other issues running the game on my computer till this track came up in the Tour.
My specs are:
i7-3630QM
12GB Ram
Nvidia GTX 660M 2GB
GeForce GameReady Driver 365.19
Windows 10 Home 64-bit
Cheers,
Andy
4 months later and this isn’t fixed… Heavy lag on rio continues…
Have you guys tried going into the task manager “details” tab after launching the game, then select forzamotorsportapex.exe and try the lowest priority possible? This is the only way to get Rio playable for me. If that doesn’t help, try the other direction and max out the priority. Maybe one of them will help.