Low FPS after 20 minutes of playing on iMac

[hueykohwf]

Your system information

* System information from steam (Steam -> Help -> System Information) in a gist:

``` Computer Information: Manufacturer: Apple Model: iMac18,2 Form Factor: Desktop No Touch Input Detected Processor Information: CPU Vendor: GenuineIntel CPU Brand: Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz CPU Family: 0x6 CPU Model: 0x9e CPU Stepping: 0x9 CPU Type: 0x0 Speed: 3600 Mhz 8 logical processors 4 physical processors HyperThreading: Supported FCMOV: Unsupported SSE2: Supported SSE3: Supported SSSE3: Supported SSE4a: Unsupported SSE41: Supported SSE42: Supported AES: Supported AVX: Supported AVX2: Unsupported AVX512F: Unsupported AVX512PF: Unsupported AVX512ER: Unsupported AVX512CD: Unsupported AVX512VNNI: Unsupported SHA: Unsupported CMPXCHG16B: Supported LAHF/SAHF: Supported PrefetchW: Unsupported Operating System Version: MacOS 10.15.4 (64 bit) Video Card: Driver: Radeon Pro 560 Driver Version: 1.2 OpenGL Version: 2.1 Desktop Color Depth: 32 bits per pixel Monitor Refresh Rate: 0 Hz VendorID: 0x1002 DeviceID: 0x67ef Revision: 0xc0 Number of Monitors: 2 Number of Logical Video Cards: 1 Primary Display Resolution: 2048 x 1152 Desktop Resolution: 4096 x 2304 Primary Display Size: 18.86" x 10.59" (21.61" diag) 47.9cm x 26.9cm (54.9cm diag) Primary VRAM: 0 MB Memory: RAM: 16384 Mb VR Hardware: VR Headset: None detected Miscellaneous: UI Language: English Media Type: DVD Total Hard Disk Space Available: 5749018 Mb Largest Free Hard Disk Block: 216100 Mb ```

• Have you checked for system updates?: Yes
• Are you using the latest stable video driver available for your system? Yes
• Have you verified the game files?: Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large pastes as a Github Gist.

After opening Dota 2, my FPS for the first 20 minutes of the game will be okay, hovering around 130 fps - 140 fps. After 15-20 minutes, the FPS will drop to around 20

-30fps, making it unplayable. The FPS reports from the console as 130fps, but its intermittently dipping to 20-30fps every 0.1seconds.

Steps for reproducing this issue:

1. Open Dota 2 on Mac OSX.
2. Play a public game or spectate a public game for 15-20 minutes.
3. The FPS will drop.

2020-05-01 21.03.24.mp4.zip

[hueykohwf]

Adding on, after running dota for 20 minutes will result in my entire Mac running sluggish until a restart. It results in other games running really slowly during this period of time.

For example, CS:GO runs at 30 FPS instead of my usual 120 FPS.

[hueykohwf]

Both OpenGL and Vulkans seems to give the same results :/

[stefanriest]

it seems to be a problem, maybe a endless loop, or something I don't know. after a while the kernel_task goes up to 1300% CPU, but at first you play the game perfectly, then the FPS drops to like 1 FPS and like after 5min it goes back to 15-30 fps.

I got a iMac 2017 3,8ghz I5 with a Radeon Pro 580 and 8G Ram.

System Information

``` Computer Information: Manufacturer: Apple Model: iMac18,3 Form Factor: Desktop No Touch Input Detected Processor Information: CPU Vendor: GenuineIntel CPU Brand: Intel(R) Core(TM) i5-7600K CPU @ 3.80GHz CPU Family: 0x6 CPU Model: 0x9e CPU Stepping: 0x9 CPU Type: 0x0 Speed: 3800 Mhz 4 logical processors 4 physical processors HyperThreading: Unsupported FCMOV: Unsupported SSE2: Supported SSE3: Supported SSSE3: Supported SSE4a: Unsupported SSE41: Supported SSE42: Supported AES: Supported AVX: Supported AVX2: Unsupported AVX512F: Unsupported AVX512PF: Unsupported AVX512ER: Unsupported AVX512CD: Unsupported AVX512VNNI: Unsupported SHA: Unsupported CMPXCHG16B: Supported LAHF/SAHF: Supported PrefetchW: Unsupported Operating System Version: MacOS 10.16.0 (64 bit) Video Card: Driver: Radeon Pro 580 Driver Version: 1.2 OpenGL Version: 2.1 Desktop Color Depth: 32 bits per pixel Monitor Refresh Rate: 0 Hz VendorID: 0x1002 DeviceID: 0x67df Revision: 0xc0 Number of Monitors: 1 Number of Logical Video Cards: 1 Primary Display Resolution: 2560 x 1440 Desktop Resolution: 2560 x 1440 Primary Display Size: 23.58" x 13.39" (27.09" diag) 59.9cm x 34.0cm (68.8cm diag) Primary VRAM: 0 MB Memory: RAM: 32768 Mb VR Hardware: VR Headset: None detected Miscellaneous: UI Language: English Media Type: DVD Total Hard Disk Space Available: 4045882 Mb Largest Free Hard Disk Block: 372157 Mb ```

Also you I see is that the gameoverlayui is crashing after a while. kernel_task is still using a lot CPU, for NO Reason. I am not even in a game, I am just in the basic HUD with 1 - 15 fps changing..... on older versions I had 100+ there must be a serious bug on the steam or dota2 app, I have the problem also on a complete new installation of Mac OS Big Sur, I tried to reproduce on another iMac - exactly the same happens. the other one is a iMac Pro, the hardware is pretty, its only Dota and steam that make the system that slow its unbelievable.

for me it looks like that the GPU isn't even in use for the game, it looks like that all is on the CPU. I can't believe I need to play on my 10-15 fps? its not possible! do you think you can make a fix soon? do you have any ideas what the problem could be? its really annoying.

BTW i am using Vulkan, openGL is even more worse.and I already fixed the mouse frequency bug, buy putting the mouse rate to 125

[Turmfalke2]

Adding on, after running dota for 20 minutes will result in my entire Mac running sluggish until a restart. It results in other games running really slowly during this period of time.

Is this to understood as in even after closing dota 2 the system performance still suffers? Or is the 'until a restart' part related to restarting dota 2?

[stefanriest]

well for me it is like only when I start steam it doesn't matter if you restart, it always the same. after a time the fps drops massive

[Turmfalke2]

Ok, lets take a few steps back.

1. You start your mac.
2. You start steam.
3. You play for 20 minutes with good/ok performance
4. The performance deteriorates
5. You close dota 2 (top right corner, "Do you really wish to quit Dota 2?")

If you then start a different game or do something else is the performance still bad? Even after step 5? Or is back to normal and you could start dota again for 20 minutes of good performance?