Summary

This article covers what to do when Microsoft 365 apps — Word, Excel, Outlook, PowerPoint, or Teams — feel sluggish, take a long time to open, or lag during normal use. These steps address the most common causes: add-in overhead, graphics acceleration conflicts, corrupted cache files, oversized documents, and outdated Office builds.

In this guide

• 1. Check If the Problem Is One App or All Apps
• 2. Close Unnecessary Programs and Browser Tabs
• 3. Disable Hardware Graphics Acceleration
• 4. Check for and Install Office Updates
• 5. Audit and Disable Unnecessary Add-Ins
• 6. Clear the Office Cache
• 7. Reduce File Size and Complexity
• 8. Check Antivirus Real-Time Scanning
• 9. Repair the Office Installation
• 10. When to Contact IT

Before You Start

• Microsoft 365 desktop apps installed on Windows 10 or Windows 11.
• A working internet connection (some steps require downloading updates).

Instructions

1. Check If the Problem Is One App or All Apps

Before troubleshooting, narrow down the scope. A single slow app points to an app-specific issue, while slowness across all M365 apps suggests a shared cause.

1. Open each Microsoft 365 app you use regularly — Word, Excel, Outlook, PowerPoint, and Teams.
2. Create a new blank document or message in each app and type a few sentences. Note whether the lag occurs in all apps or only one.
3. If only one app is slow, the problem is likely app-specific — a problematic add-in, a large file, or corrupted app data. Focus on Steps 3, 5, and 7 for that specific app.
4. If all apps are slow, the problem is shared — graphics acceleration, Office cache, Office updates, or antivirus interference. Focus on Steps 3, 4, 6, and 9. If your web browser and other non-Office programs are slow too, the cause is the PC rather than Office — see How to Fix Slow Performance on Windows 11.

2. Close Unnecessary Programs and Browser Tabs

Microsoft 365 apps share system memory (RAM) with everything else running on your PC. If your system is low on available memory, all apps will slow down.

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Click the Memory column header to sort by memory usage (highest first).
3. Look for programs consuming large amounts of memory — web browsers with many tabs, other Office apps you are not using, or background apps.
4. Close any unnecessary browser tabs. Each tab consumes 50–300 MB of memory. A browser with 30+ tabs open can use several gigabytes.
5. Close any Microsoft 365 apps you are not actively using. Each open Office app runs its own process and loads its own add-ins.
6. If Task Manager shows your PC is using more than 85–90% of total memory, closing programs is the most impactful thing you can do.

3. Disable Hardware Graphics Acceleration

Hardware graphics acceleration uses your GPU to render the Office interface. On some PCs — especially those with older or integrated graphics cards — this causes UI lag, slow scrolling, and delayed rendering instead of improving performance.

1. Open any Microsoft 365 app (Word, Excel, or PowerPoint).
2. Go to File > Options > Advanced.
3. Scroll down to the Display section.
4. Check the box for Disable hardware graphics acceleration.
5. Click OK and restart the app.
6. Test whether performance improves. This setting applies to Word, Excel, and PowerPoint. Outlook has a separate setting: File > Options > Advanced > Display > Disable hardware graphics acceleration.
7. If disabling acceleration makes things worse (rare), uncheck the box to re-enable it.

4. Check for and Install Office Updates

Outdated Office builds can contain known performance bugs that Microsoft has already fixed in newer updates.

1. Open any Microsoft 365 app.
2. Go to File > Account (or File > Office Account).
3. Under Product Information, click Update Options > Update Now.
4. If updates are available, let them download and install. You may need to close all Office apps during the update.
5. After the update completes, reopen your apps and test performance.
6. If Update Options is greyed out or missing, your organization manages updates through IT — they will be installed automatically during your next update window.

5. Audit and Disable Unnecessary Add-Ins

Add-ins load into Office apps at startup and run in the background. Antivirus plugins, CRM connectors, PDF converters, and other third-party add-ins are frequent causes of slowness.

1. Open the slow app (e.g., Word, Excel, or Outlook).
2. Go to File > Options > Add-ins.
3. At the bottom, next to Manage, select COM Add-ins and click Go.
4. Note which add-ins are checked (enabled). Uncheck all add-ins and click OK.
5. Restart the app. If it is noticeably faster, one or more of the disabled add-ins was the cause.
6. Re-enable add-ins one at a time, restarting the app after each, until the slowness returns — that add-in is the culprit.
7. Leave the problem add-in disabled. If it is a business-critical tool, report the performance issue to IT.
8. Repeat this process for each slow app — add-ins are configured per-app (Word has its own list, Excel has its own, and so on).

6. Clear the Office Cache

Office stores temporary files, upload data, and document metadata in a local cache. A corrupted or oversized cache can slow down file operations — opening, saving, and syncing documents.

1. Close all Microsoft 365 apps.
2. Press Win + R, type %localappdata%\Microsoft\Office\16.0 and press Enter.
3. Look for a folder called OfficeFileCache. If it exists, delete everything inside it (not the folder itself).
4. Press Win + R, type %localappdata%\Microsoft\Office\16.0\Wef and press Enter. If this folder exists and contains files, delete the contents — these are cached web add-in files.
5. Reopen your Microsoft 365 apps. Office will rebuild the cache automatically.
6. For Outlook specifically, if Outlook is slow, also consider reducing the cached mailbox window — go to File > Account Settings > Account Settings, select your account, click Change, and reduce the Mail to keep offline slider from All to 12 months or 6 months. Outlook also has causes this article does not cover, including an oversized data file and too many connected shared mailboxes — for those, see How to Fix Outlook Running Slowly.

7. Reduce File Size and Complexity

Large or complex files are one of the most common causes of app-specific slowness — especially in Excel and PowerPoint.

Excel:

1. Check file size — if your workbook is over 10 MB, it may cause lag.
2. Look for volatile formulas that recalculate on every edit: INDIRECT(), OFFSET(), NOW(), TODAY(), RAND(), and RANDBETWEEN(). Replace them with static values or non-volatile alternatives where possible.
3. Check for excessive conditional formatting. Select a large range, go to Home > Conditional Formatting > Manage Rules and look for hundreds of overlapping rules.
4. Remove unused worksheets and named ranges.
5. If the workbook contains images, compress them: select an image, go to Picture Format > Compress Pictures, and choose Web (150 ppi).

PowerPoint:

1. Large image and video files embedded in slides cause stuttering during editing and presentation mode.
2. Compress all images: go to File > Info > Compress Media or select an image and use Picture Format > Compress Pictures.
3. Convert embedded videos to a lower resolution if high quality is not needed.

Word:

1. Documents with hundreds of tracked changes or comments slow down significantly. Accept or reject all tracked changes if the review is complete: go to Review > Accept > Accept All Changes.
2. Large embedded images slow down scrolling. Compress images: select one, go to Picture Format > Compress Pictures, and apply to all pictures in the document.

8. Check Antivirus Real-Time Scanning

Antivirus software that scans every file on read and write can dramatically slow Office apps — especially when Office creates temporary files during editing.

1. If you notice that Office apps are slow to open files, slow to save, or pause briefly during auto-save, real-time antivirus scanning may be the cause.
2. Check whether your antivirus software has a way to exclude specific folders or file types from real-time scanning.
3. Common exclusions that help Office performance (ask IT before making changes if your organization manages antivirus):
   • %localappdata%\Microsoft\Office — Office temporary files
   • %localappdata%\Microsoft\Outlook — Outlook data files (OST)
   • %appdata%\Microsoft\Templates — Office templates
4. If you cannot configure exclusions yourself, report the performance issue to IT and mention that you suspect antivirus scanning is involved — they can configure exclusions centrally.

9. Repair the Office Installation

If individual app fixes do not help, the shared Office installation files may be corrupted.

1. Close all Microsoft 365 apps.
2. Press the Start key, type Installed Apps, and press Enter.
3. Search for Microsoft 365 (or Office).
4. Click the … (three dots) next to it and select Modify.
5. Select Quick Repair and click Repair. This takes 5–10 minutes and does not require internet.
6. Reopen your apps and test performance.
7. If Quick Repair did not help, repeat the process and select Online Repair instead. Online Repair takes 15–30 minutes and requires internet, but it completely reinstalls Office while preserving your data and settings.

10. When to Contact IT

Name the pattern in your ticket — every app slow, one app slow, or slow only on VPN — because each one points at a different fix. If antivirus scanning was the pattern that matched, ask them to add the folder paths from Step 8 to the central exclusion list.

Contact your IT helpdesk if:

• All Microsoft 365 apps remain slow after running Online Repair — the issue may be hardware-related (insufficient RAM, failing hard drive) or related to group policy settings that you cannot change.
• Apps are slow only when connected to VPN or a remote desktop session — network latency affects cloud-synced features (autosave, co-authoring, Teams) and is an infrastructure issue.
• You suspect antivirus real-time scanning is the cause but cannot configure exclusions yourself — IT can add exclusions to the centrally managed antivirus policy.
• Your PC has fewer than 8 GB of RAM and runs multiple Office apps simultaneously — IT may need to approve a hardware upgrade. To find how much your PC has before you raise the ticket, see How to Check Your Computer's Specs (RAM, CPU, and Storage) on Windows.
• Performance degraded immediately after an Office or Windows update and has not recovered after installing the latest updates — IT can check if a known issue exists and apply a targeted fix.

Troubleshooting

DANGER

If all Microsoft 365 apps are slow but your web browser runs normally, focus on hardware acceleration (Step 3), add-ins (Step 5), and Office repair (Step 9). If only one app is slow, focus on that app's add-ins (Step 5) and file complexity (Step 7).

Symptom / Error	Potential Cause	Solution
Word takes 30+ seconds to open any document	Add-ins loading at startup or antivirus scanning	Disable add-ins (Step 5) and check antivirus exclusions (Step 8).
Excel lags when scrolling or editing	Volatile formulas or excessive conditional formatting	Reduce file complexity (Step 7 — Excel section).
All Office apps slow, but browser is fast	Shared Office issue — acceleration, cache, or install	Disable hardware acceleration (Step 3) and run repair (Step 9).
Apps slow only when connected to VPN	Network latency affecting cloud sync	Ask IT to check how Microsoft 365 traffic is routed over the VPN, and name which apps slow down (Step 10).
Apps slow after a recent Office update	Update regression	Check for a newer update (Step 4) or run Online Repair (Step 9).
PowerPoint stutters during slideshow	Uncompressed media or hardware acceleration	Compress media (Step 7 — PowerPoint) and disable acceleration (Step 3).
Typing in Word or Outlook has a visible delay	Add-in interference or low system memory	Close other apps (Step 2) and disable add-ins (Step 5).

Related Articles

• How to Fix Slow Performance on Windows 11
• How to Fix Outlook Not Responding or Freezing
• How to Fix Excel Crashing or Freezing
• How to Fix "Product Activation Failed" and License Errors in Microsoft 365 Apps
• How to Use Keyboard Shortcuts to Work Faster in Windows and Microsoft 365
• How to Fix Common Computer Glitches by Restarting

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