Question Please help with understading FPS stability issue in Competitive Gaming - Fortnite on High End PC

Sep 14, 2020

I need some help to understand why I still experience FPS stability issues (FPS drops) in certain Fortnite game situations while CPU, GPU utilization are low (never exceeding 20%). and temperature below 55C for both.

Please find below context, config + settings information, and questions down below.


I play Fortnite with high end PC that can reach max Framerate of 500-600 FPS (Fortnite Creative mode), up to 350-400 FPS (Battle Royale mode). But prefer to cap FPS at 237 in game all the time, for all game modes, to ensure consistent experience (for aim etc).

But average FPS can drop to 30 for 1 second, or to 120FPS for 5 seconds or 10 seconds, in certain game situations (early game, jumping from bus, scouting), while utilization of both CPU & GPU + temps are low.

My config:

CPU: 9900K 8cores 16threads (Hypethreading on, Turbo boost on)
GPU: 2080TI
RAM: 16GB 3600MHZ CL16
OS: Windows 10 Pro.
Monitor: AW2521HFL 240HZ with Gsync Compatible
Keyboard: Logitech G513 Romer G.
Mouse: Logitech G203, Polling rate: 1000Hz. DPI: 800.
Headset: Logitech Gaming Pro

  • 1920x1080, resolution 100%
  • View: Epic, all rest set to low (although Texture & Antialiasing can be set to Epic with zero impact on FPS. Tried it while testing uncapped with no Gsync or Vsync)
  • Multithreaded rendering On. All the rest off (vsync off, motion blur off, High definition resolution off..etc).
NVIDIA Control Panel Settings (use blurbusters low input lag advice: Gsync On + Vsync On + LLM On + Ingame Gap 237FPS ==>

Image SharpeningOff
Ambiant OcclusionOff
Anistropic FilteringOff
Antialiasing - FXAAOff
Antialiasing - Gamma CorrectionOn
Antialiasing - ModeOff
Antialiasing - SettingOff
Antialiasing - TransparencyOff
Cuda - GPUsAll
DSR FactorsOff
Low Latency ModeOn
Max Frame rateOff
Monitor TechnologyGsync Compatible
Open GL Rendering GPURTX 2080Ti
Power Management ModePerfer Maximum Performance.
Preferred Refresh rateHighest available
Shader CacheOn
Texture Filtering - Anistropic Sample OptimizationOn
Texture Filtering - Negative LOD BiasAllow
Texture Filtering - QualityHigh Performance
Texture Filtering - Trilinear OptimizationOn
Threaded OptimizationAuto
Tripple BufferingOff
Vertical syncOn
Virtual Reality pre-rendered frames1
Virtual Reality - Variable Rate SuperOff
Configure Surround PhysxRTX 2080Ti
Adjust Desktop Size & Position (scaling)Perform Scaling on Display + No Scaling + Override the scaling mode set by games

Power Mode:
Bitsum Highest activated via Process Lasso.

Windows Graphics Tweaks:
Game Mode: On
Hardware Accelerated GPU Scheduling: Off
Graphics Performance Preference: set to High performance for all Fortnite executables (Fortnite.exe, Fortnite launcher.exe, Fortnite easyanticheat.exe, Battleeye.exe..etc).
Disabled HPET in device Manager
Use ISLC With 0.5ms Timer Resolution (I sometimes disable it, because it causes more fps drops then when off, dont know why).

Windows RegistryTweaks:

- CPU Optimization:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile]

- Disabling MMCSS:

- Higher GPU Priority for Games:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games]
"GPU Priority"=dword:00000008
"Scheduling Category"="High"
"SFIO Priority"="High"

- Power Optimizations:









Problem: while I have no issues at all in terms of FPS Stability in Creative Mode, I experience drastic FPS drops (sudden FPS drops from 237 to 20 FPS for 1sec OR average FPS becomes 120FPS for 10 seconds or 20 seconds at the start of the game, or in the middle of the game / or during some intense fights with many players) while hardware utilization is low CPU at 20%

Software I use to try to monitor overall performance:
  • LatencyMon (for Driver & Processes DPC latency monitoring), all is green and seems to work perfectly.
  • MSI Afterburner + Rivatuner (for real time graphics performance monitoring)
  • Nvidia FrameView (for graphics performance analysis)
  • Windows Performance Analyzer
  • GPU-Z
  • HwMonitor
  • Mouse Tester v1.5
Software I use to try to Tweak performance:
  • Process Lasso (bitsum highest profile, all apps use
  • Quick CPU
  • ISLC
  • NVCP
  • MSI Mode Utility2 (GPU set to MSI High)
  • Affinity Policy (I put the GPU Interrupts on GPU 14 & 15 => Core+Thread. Mouse & Keyboard USB hub on GPU 2 & 3 => Core+Thread).
  • All drivers have been installed with the latest from manufacturers' websites (Nvidia using DDU).
  • I deactivated many windows services, but this doesnt seem to be the issue at all
  • I set the sound quality to 16 bis 48000Hz and deactivated the High definition audio of the motherboard since I go through the Logitech Usb Ghub (instead of jack).
  • I debloated windows from all of the apps (Cortana, etc), deactivated all apps, notifications,
  • Adjusted the Windows Visual Effects to "Best for Performance"
  • Virtual Memory/Paging, set to Custom Size: 16gb to 32Gb (since I have SSD).
  • Disabled full screen optimizations + High DPI Scaling "Override high DPI Scaling behavior" Scaling performed by "Application". on FortniteClient-Win64-Shipping.exe
  • My internet speed gets me a 25 Ping and 8mb/s.
  • Disabled mouse acceleration (from mouse settings & in registry) and set the cursor on speed 6.
  • I play fortnite on DirectX 11, because DirectX 12 brings more frequent and irritating FPS Drops (never understood why).
- Could the fact that many online players are located in the same 3d arena in the game explain the FPS drops (such as in early game while waiting for bus in Fortnite, or when jumping from the bus at a crowded area; where FPS drops from 237FPS, to ~120FPS average, the more players appear, or while scouting with the mouse. Since as soon as I get in a less crowded arena say 2 or 3 players, or in empty areas, the FPS is stable at 237 when capped, and can go up to 400FPS when uncapped+vsync off)? How come since the CPU and GPU are barely utilized (<20%) and the ping+bandwidth do not seem to impact FPS at all. Can this be related to the NDIS.SYS Driver for example?

- To which extent does sound frequency or game sound effects impact FPS? Where does that translate? How can that be identified and fixed? As I do not see any impact in FPS Stability when changing the quality or the frequency of sound.

- Does Mouse polling rate stability influence FPS? How? Using Mouse Tester v1.5, I noticed that within 1sec, the polling rate can have a variability of 200Hz on average, from the 1000Hz set in Logitech Ghub software. I saw that this variability could be reduced (to reach 2Hz or max 5Hz variability) by changing the Interrupt affinity of the Mouse USB Hub, that I set to CPU 2&3. Although I tested changing the affinity with various CPU cores/threads, I could not figure out a way to improve this, at the same time, I am doubtful about the relationship between polling rate variability & FPS Stability.

- Since Fortnite is a CPU Based game, can CPU features like Turbo boost or Hyperthreading, impact negatively.

- Could this FPS Stability issue be coming from Fortnite Servers themselves? How, from a technical perspective ? Since Fortnite officially states that these issues are mainly related to the player's PC setup.

- What is the best tool or set of tools to perform a precise root-cause analysis for FPS drops. I want to be able to view the precise moment when the FPS dropped, and pin point the exact relevant factor that brought the performance decrease: power voltage? CPU? Windows or Device Driver? Specific Process? Since this problem is recurring, meaning, the FPS always drops the same way in the same situations (for example crowded areas).
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