Large PDF file slow searching

I have found a way to fix a problem that I had, but I don't know if it will fix the same problem that you have as well. I had an issue where Adobe's search function was incredibly slow to find text within a PDF document or multiple documents. I found a way to make regular searching and advanced searching for text in PDF documents faster to the point where the search results are displayed almost instantaneously. Before this fix, searching could take 2 to 3 minutes to find all the strings of text within a folder containing 5 PDF files that were each about 700 pages in size.

Here are the steps to perform the fix:

1.) Open Adobe Reader directly (do not open it by opening a file such as a PDF to open. If Adobe Reader is already open, close it and make sure it is completely closed [not running in the background]).

2.) Go to Edit > Preferences.

3.) Under Categories: click on Documents.

4.) Under the "Open Settings" make sure that the "Restore last view settings when reopening documents" box is unchecked. If it is unchecked, continue to the next step. If it is checked, uncheck it, click the OK button at the bottom, and restart Adobe again directly.

5.) Under Categories: click on Search.

6.) Under the "Fast Find" area, click on the "Purge Cache Contents" button, then make sure the "Enable fast find" box is checked, and lastly, increase the Maximum Cache Size: to at least 1000 MB. (the default size should be 100 MB).

7.) Click the OK button at the bottom, and restart Adobe again directly.

8.) Open all of the documents you want to search text for and type a string of text that will appear somewhere in the document, or documents. (the searching might take 5 to 10 minutes or longer for big documents or when searching a folder with multiple PDFs).

9.) Wait for the searches to complete.

10.) Go back into Edit > Preferences > Under Categories: click on Documents.

11.) Under the "Open Settings" check the "Restore last view settings when reopening documents" box, and click the OK button at the bottom.

12.) Repeat steps 8 and 9.

13.) Restart Adobe again directly.

(note: increasing the Maximum Cache Size from 100 MB might be optional, I am not 100% sure about this.)

I have different versions of Adobe running on different computers including reagular Adobe Acrobat Reader, and Adobe Acrobat Reader DC. On all of the versions I have, this fix worked for me. I hope this helps.

Hello, this is a late reply, but I would suggest you to search and try:

• Embedded index tool (Also see if small/large pdf file have index inside)
• After ctrl+f click gear icon and try searching in advanced search

In other case,  if you have two similar length pdf files, and if one file is searching fastly while the other is searching slowly, I would suggest you to check if two files have been generated at similar years. If these do not yield results, I do not know the cause of this issue.