I've been running into a notorious problem with Adobe InDesign on Windows (specifically CC 2020 through 2026+).
Sometimes InDesign is completely idle — no active export, no rendering, no document modifications — but one CPU core remains pinned at 100% (showing as 15% to 25% total CPU in Task Manager depending on core count). Laptop fans spin constantly, battery life drains, and InDesign starts feeling sluggish.
Looking at individual threads of the InDesign.exe process, the runaway CPU usage is almost always caused by a background worker thread (often tied to font caching, Torq typography engine, or CEP/UXP panel communication) stuck in an infinite polling loop.
I created an open-source Windows utility to resolve this: ID_Thread_Fix.
How it works (v1.2 update):
- Attaches to InDesign (or acts as a drop-in launcher for InDesign and opened
.indd documents).
- Waits for InDesign's main window to appear, plus an extra 25-second grace period so font engines, Torq typography, and CEP extensions can complete their initial startup burst undisturbed.
- Samples individual thread CPU usage over 2.0 seconds.
- Deliberately protects InDesign's main UI thread and primary process thread — they are never touched.
- Identifies background threads stuck at excessive CPU load (60%+ of a core during idle).
- Safely freezes runaway threads using the Win32
SuspendThread API (instead of terminating them).
Why SuspendThread is critical:
Earlier attempts at terminating threads via TerminateThread could cause intermittent crashes (Access Violation 0xc0000005 in ntdll.dll) because forcefully terminating a thread abruptly abandons internal critical sections and heap locks.
In contrast, suspending the thread simply halts its execution cycles:
* CPU consumption instantly drops from 20%+ to ~0% idle and fans go silent immediately.
* Internal memory structures, handles, and locks remain completely intact and stable — zero crash risk.
Before / After:
In testing on idle InDesign instances:
* Before: 18% - 25% CPU (one full core pegged, fans spinning).
* After: ~0.3% CPU (fans quiet, InDesign completely responsive).
Where to get it:
The utility is completely free and open source:
* GitHub: GitHub — ID_Thread_Fix
* Direct Download & Info: ph-cu-s.com/tools/id-thread-fix
It is a tiny standalone portable executable (328 KB) with zero dependencies. No installer or runtime setup needed. You can use it as a desktop shortcut replacement or run it with --fix-only to instantly tame an already-running, lagging InDesign instance.
Important note: This is a community workaround, not an official Adobe patch. Always save your work before testing new tools.
Feedback:
If you have been experiencing this runaway idle thread issue in InDesign, I would love to hear your feedback:
* InDesign version
* Windows version
* CPU model
* Whether the fix resolved the CPU load for you
Hopefully this saves your CPU temps and laptop battery until Adobe properly addresses the underlying background loop!