PDF Editing Issues

How to Fix Lag When Highlighting or Underlining Text in Adobe Acrobat

Adam Davis Oct 19, 2026 868 views

Question details

Users experience noticeable delays and lagging performance when attempting to highlight or underline text in PDF documents.

How to Fix Lag When Highlighting or Underlining Text in Adobe Acrobat

Product: Adobe Acrobat Premium
Device & OS: not provided
Scenario: Annotating or editing a PDF document by adding highlights and underlines to the text.
Observed behavior: The application lags and responds slowly to highlighting or underlining commands, which may affect a single specific file or occur across all documents after upgrading.

Before you start

Before troubleshooting, check if the lagging issue happens with only one specific PDF or across all your documents, as unusually large or corrupted files can independently cause performance issues.

Solution 1Recommended

Clear App Cache and Update Operating System

Resolve performance lags by clearing temporary app data and ensuring your device software is fully updated to the latest version.

Accumulated cache files and outdated operating systems are common culprits for application performance drops. Refreshing the application data and keeping the OS updated ensures maximum compatibility and smooth operation for heavy tasks like PDF annotation.

Close the application

Close the Adobe Acrobat application completely, ensuring it is not running in the background.

Clear the application cache

Navigate to your device's settings menu, locate the application manager or apps list, select Adobe Acrobat, and tap or click on the 'Clear Cache' option.

Update your operating system

Go to your device's system settings, check for any pending operating system updates, and install them.

Restart and test

Restart your device, launch Adobe Acrobat, and try highlighting or underlining text in your PDF file again to see if the lag has been resolved.

Clear App Cache and Update Operating System

Gathering Diagnostic Information: If the issue persists, gather your device model, OS version, Adobe Acrobat version, and file-specific behavior to provide to Adobe Support for further troubleshooting.

Smooth PDF Editing Experience

Highlight and Underline PDFs Smoothly with WPS Office

If Adobe Acrobat continues to lag, switch to WPS Office. Its built-in PDF editor is highly optimized and lightweight, allowing you to easily highlight, underline, and annotate large PDFs without any performance drops.

1. Open WPS Office: Launch the WPS Office application on your computer or mobile device.
2. Open your PDF file: Click on 'Open' and select the PDF document you wish to read and annotate.
3. Navigate to the Comment tab: On the top toolbar, click on the 'Comment' tab to access the annotation tools.
4. Highlight or underline text: Select the 'Highlight' or 'Underline' tool, pick your preferred color, and smoothly drag your cursor over the text.

Lightweight architecture ensures zero lag during PDF reading and annotationEasily highlight, underline, and add customized comments to any PDF fileFully compatible with standard PDF formats and Adobe Acrobat filesFree to use across multiple platforms with seamless cloud synchronization

Frequently Asked Questions

Why does Adobe Acrobat lag only on certain PDF files?

Certain PDF files may contain high-resolution scanned images, complex hidden layers, or missing embedded fonts that require extra processing power, causing the application to slow down when applying annotations.

Will reinstalling Adobe Acrobat fix the highlighting delay?

Yes, uninstalling and freshly reinstalling the application can resolve corrupted installation files or conflicting background processes that lead to performance lags.

How do I know what version of Adobe Acrobat I am using?

You can find your version number by opening Adobe Acrobat, clicking on the 'Help' menu at the top, and selecting 'About Adobe Acrobat'. On mobile devices, this is usually found in the app settings under 'About'.

PDF Troubleshooting