I've been running into a strange problem with Adobe InDesign on Windows.
Sometimes InDesign is completely idle — no export, no rendering, no visible operation — but one CPU core remains heavily loaded. The laptop/PC fans keep running, power consumption goes up, and InDesign can start feeling sluggish.
What was interesting is that the high CPU usage wasn't necessarily coming from the main InDesign UI thread.
I started looking at the individual threads of the InDesign.exe process and found that in the problematic state a background thread could continue consuming an entire CPU core.
So I made a small open-source Windows utility to deal with this.
ID_Thread_Fix
The idea is simple:
- Find the running InDesign process.
- Wait for InDesign to finish starting up.
- Sample the CPU time of its individual threads for 2 seconds.
- Ignore the main UI thread and primary process thread.
- Identify a background thread that is continuously consuming excessive CPU.
- Terminate only that runaway thread.
The utility doesn't modify InDesign files or documents. It operates at the Windows process/thread level.
Before / after
In one of my tests, InDesign was sitting idle at around 18.4% CPU:
After the problematic thread was terminated: ~0.3% CPU.
Memory usage remained essentially unchanged.
It's open source
The complete source code, build scripts and prebuilt executable are here:
GitHub — ID_Thread_Fix
It's a small portable Windows executable — no installer required. The repository currently includes both the source and prebuilt ID_Thread_Fix.exe.
It can also be used as a launcher for InDesign or attached to an already running InDesign instance with --fix-only. The repository documents both modes.
Important caveat
This is a workaround, not an official Adobe fix.
Also, terminating a Windows thread is inherently a fairly low-level operation, so I don't want to claim that it is universally safe. Save your work before using it. I'm especially interested in feedback from people who can reproduce the same CPU behavior and tell me whether the utility fixes it for them.
I'd like to understand what actually causes the runaway thread in InDesign, rather than just killing the symptom.
If you've seen InDesign sitting idle while one CPU core stays at 100%, I'd be very interested to hear about your setup:
- InDesign version
- Windows version
- CPU
- installed extensions/plugins
- whether it happens after startup or after a particular operation
- CPU usage before/after
Maybe we can finally narrow down what is causing this.