Fixing SimHub dashboard lag and FPS drops
Last updated · SimHub 9.11.22
SimHub renders dashboards through WPF, which is GPU-accelerated, so it competes with your game for the same hardware. If the GPU is already at 90–95% load, a dashboard has nothing left to draw with. Cap the game's frame rate first — that one change fixes most cases. After that, the usual causes are G-Sync or FreeSync interfering with rendering, mismatched refresh rates across monitors, process throttlers like Game Mode or Process Lasso deliberately starving non-game applications, and overlays larger than SimHub's 480,000-pixel limit allows for.
Almost none of this is the dashboard's fault, which is why redesigning it rarely helps. Work down the list — it is ordered by how often each is actually the cause.
1. The GPU is already full
This is the big one. SimHub's rendering is hardware-accelerated, which is what makes dashboards smooth, and it means SimHub needs GPU time. A game running at 95% GPU utilisation has not left any.
The symptom is characteristic: the game runs fine on its own, and both the game and the dashboard stutter once SimHub is displaying something.
- Cap the game's frame rate. A limiter set slightly below what your GPU can manage leaves headroom for everything else. This single change resolves the majority of cases.
- Check actual GPU load while both are running, rather than assuming. Anything sustained above 90% is the answer.
- Drop a graphics setting. Any setting — the point is headroom, not which slider you moved.
A frame-rate cap is not a compromise here. Frames your GPU produces while it is saturated are also the least consistent ones. Capping usually improves frame pacing at the same time as freeing capacity for SimHub, which is why it is worth doing even without a dashboard.
2. G-Sync and FreeSync
Adaptive sync interferes with how WPF renders, and this catches people out because everything else about their system is well configured.
Adaptive sync works by varying the display's refresh to match the game. SimHub is a separate application drawing at its own rate onto a display whose timing is being driven by something else, and the two do not reconcile cleanly.
- Set adaptive sync to fullscreen-only in the NVIDIA or AMD control panel, rather than fullscreen and windowed.
- Or add a SimHub exception, so adaptive sync does not apply to it.
- Or disable it on the secondary monitor if your dashboard lives on one — you almost certainly do not need variable refresh on a display showing numbers.
3. Mismatched monitor refresh rates
A 144Hz main monitor next to a 60Hz secondary is a common sim racing setup and a known source of stutter. Windows composites across both, and mismatched timings produce hitching that appears in the game rather than on the secondary display where the mismatch lives.
Set all connected monitors to the same refresh rate and retest. If that fixes it, you can then decide whether you would rather have the higher rate or the smoothness — but at least you will know which you are choosing.
4. Software that deliberately starves SimHub
Several utilities exist specifically to give games priority by suppressing everything else. SimHub is exactly the kind of thing they suppress.
| Software | What it does | Fix |
|---|---|---|
| Windows Game Mode | Prioritises the foreground game | Turn it off, or test with it off |
| Process Lasso | Throttles background processes by rule | Add a SimHub exclusion |
| Norton Game Optimizer | Restricts non-game processes | Exclude SimHub |
| MSI X3D Mode | Manages core assignment for gaming | Test with it disabled |
These are worth checking precisely because they are supposed to be helping. A user who installed a game optimiser to improve performance is unlikely to suspect it of causing a performance problem.
5. Oversized overlays
Overlays have a hard size limit: width × height must not exceed 480,000 pixels. 800×600 is fine at 480,000 exactly. 800×800 is 640,000 and is rejected. This is a real limit rather than a guideline, and it exists because overlay surfaces are expensive to composite.
The subtlety people miss: transparent area still costs. An overlay that is mostly empty space is not cheaper than one that is full — the surface is composited regardless of what is drawn on it. Size the overlay to its content rather than making a large one and leaving most of it clear.
More on the overlays page.
6. Try the alternative rendering engine
This is the least-known useful fix on the page. SimHub offers an alternative HTML rendering engine, selectable per dashboard through the settings gear on that dashboard.
It is worth trying when one specific dashboard misbehaves and others are fine — that pattern points at how that dashboard is being rendered rather than at your system. Switching engines costs nothing and takes seconds.
If every dashboard is equally bad, this will not help; go back to GPU load.
Other causes worth knowing
- Antivirus. Avast and Norton have both been implicated in SimHub performance problems specifically. A folder exclusion is the test.
- Telemetry recording. If you have recording enabled and forgot, it is writing continuously. Turn it off unless you are using it.
- Laptop GPU assignment. On a machine with integrated and discrete graphics, Windows may be running SimHub on the integrated GPU. Assign it explicitly to the discrete one in Windows' graphics settings.
- Power plan. A balanced or power-saving plan can downclock during what Windows reads as light load. Use the high-performance plan.
- Third-party plugins. The usual suspects — a plugin polling aggressively costs CPU continuously. Disable them and retest.
Common questions
Why does SimHub cause FPS drops?
It renders through WPF on the GPU, so it competes with your game for the same hardware. If the GPU is already at 90–95% load there is nothing left. Capping the game's frame rate slightly below what the GPU can manage fixes the majority of cases.
Does G-Sync affect SimHub?
Yes. Adaptive sync interferes with how WPF renders. Set G-Sync or FreeSync to fullscreen-only rather than fullscreen and windowed, add a SimHub exception, or disable variable refresh on the monitor showing the dashboard.
Why does my dashboard stutter on a second monitor?
Often mismatched refresh rates. A 144Hz main monitor alongside a 60Hz secondary produces compositing hitches that show up in the game rather than on the secondary display. Set all monitors to the same refresh rate to test.
What is the maximum overlay size in SimHub?
Width multiplied by height must not exceed 480,000 pixels. 800×600 is exactly at the limit and works; 800×800 is 640,000 and is rejected. Transparent area counts — an overlay that is mostly empty costs the same as a full one.
What is the alternative HTML rendering engine?
A second rendering path SimHub offers, selectable per dashboard from that dashboard's settings gear. It is worth trying when one dashboard misbehaves while others are fine, since that pattern points at rendering rather than at your system.
Can Windows Game Mode cause SimHub problems?
Yes. Game Mode, Process Lasso, Norton Game Optimizer and MSI X3D Mode all deliberately restrict non-game processes — which is exactly what SimHub is. They are easy to overlook because they were installed to improve performance.
Sources
Related guides
SimHub is developed independently by Wotever and is not affiliated with oesimracing. This page was checked against SimHub 9.11.22 on 4 August 2026; where the interface has moved on since, the version stamp tells you how far. More on what SimHub is and what it costs.