Performance issues with Windows IoT Enterprise on custom hardware
Problem description
After deploying Windows IoT Enterprise 2025 on a custom ARM‑based board, we notice a significant drop in CPU and I/O performance compared to the reference hardware. The system appears sluggish during startup and when running real‑time data acquisition tasks.
Symptoms
- CPU utilization stays near 100 % even at idle.
- Disk I/O latency > 200 ms on the eMMC.
- Network throughput limited to ~5 Mbps.
- Frequent “Power Throttling” warnings in the Event Viewer.
What we’ve tried
- Updated BIOS to the latest firmware (v2.3).
- Disabled unnecessary services (Print Spooler, Windows Search).
- Applied the
PowerThrottlingMode=0registry tweak. - Re‑installed with the “IoT Core Optimized” image.
These steps have not resolved the issue.
Possible causes
Below are some commonly observed causes for performance degradation on custom boards:
- ▶️ Power management configuration
Verify that the board’s Power Management Controller (PMC) is correctly exposing ACPI _PCT and _PSS entries. Missing or inaccurate values can lead Windows to apply aggressive throttling.
- ▶️ Storage driver mismatch
Ensure the eMMC controller uses the latest MMC driver from the Windows IoT driver catalog. An outdated driver may default to a low-speed DMA mode.
- ▶️ Network adapter firmware
Check that the Ethernet PHY firmware is up‑to‑date and that the correct driver (e.g., NDIS) is installed. Improper link negotiation can cap throughput.
- ▶️ CPU microcode
Some ARM SoCs require microcode updates that are delivered via the vendor's firmware package. Without them, the CPU may run at a reduced clock frequency.
Requesting help
If you have encountered similar issues on custom hardware, please share the steps that helped you restore performance.
Comments (12)
We had a similar problem on a Cortex‑A72 board. Updating the ACPI tables resolved the throttling warnings.
Make sure the eMMC is set to HS400 mode in the firmware. The default fallback is HS200, which is much slower.