Why is Word using so much CPU?

High CPU usage is typically caused by background spell checking on large documents, add-in processes, hardware graphics acceleration issues, or corrupted document elements that Word repeatedly tries to process.

Fix: Microsoft Word Using 100% CPU

Why Word Uses Excessive CPU

High CPU usage from Word makes your entire computer sluggish. Here are the common triggers and how to fix each one.

手順

Step 1: Disable Hardware Graphics Acceleration

Go to File > Options > Advanced
Scroll to the Display section
Check Disable hardware graphics acceleration
Click OK and restart Word

Step 2: Disable Background Spell Checking

For large documents, spell checking can consume significant CPU:

Go to File > Options > Proofing
Uncheck Check spelling as you type
Uncheck Mark grammar errors as you type
Run spell check manually when needed with F7

Step 3: Check Add-ins

Open Task Manager and note Word’s CPU usage
Close Word, reopen in Safe Mode (winword /safe)
Open the same document and check CPU usage
If lower in Safe Mode, disable add-ins via File > Options > Add-ins

Step 4: Simplify the Document

If the issue is document-specific:

Try selecting all content (Ctrl+A) and pasting into a new blank document (Ctrl+Shift+V for unformatted)
If CPU normalizes, the original document has corrupted formatting
Reapply formatting in the new document

Step 5: Check for Updates

Go to File > Account > Update Options > Update Now
High CPU bugs are often fixed in Office updates

予防

Keep documents under 100 pages when possible
Compress images before inserting
Avoid deeply nested tables
Update Office regularly