Comparing two documents needs some amount of memory, that is because the text or even images of both sides must be loaded in order to be compared.
Problems with memory typically arise if
You cannot do much if you need to compare large documents or documents with many elements on a single page.
But when facing too many differences (like >10k) you should choose a different profile for your comparison or customize the used profile in order to get only the desired information.
By default a Java Program such as i-net PDFC will take 1/4 of the memory available on your system as its maximum. You can give i-net PDFC more memory if you need to compare large documents.
To do this you must set the -Xmx command line option to some larger value.
In your installation folder, open the properties of your i-net PDFC shortcut (Right-click and select Properties). In the Shortcut tab you will find the Destination like
"C:\\Program Files\\i-net PDFC GUI\\jre\\bin\\javaw.exe" -cp "C:\\Program Files\\i-net PDFC GUI\\java\\PDFCGui.jar" com.inet.pdfc.Startup
Add the Xmx option here like
"C:\\Program Files\\i-net PDFC GUI\\jre\\bin\\javaw.exe" -cp "C:\\Program Files\\i-net PDFC GUI\\java\\PDFCGui.jar" -Xmx1024m com.inet.pdfc.Startup
-Xmx must appear in front of com.inet.pdfc.Startup!
Open the executable file /usr/bin/i-net PDFC with an appropriate editor. It should look like
#!/bin/bash java -cp "/usr/share/i-net-pdfc/java/PDFCGui.jar" com.inet.pdfc.Startup "$@"
Add the Xmx option like
#!/bin/bash java -cp "/usr/share/i-net-pdfc/java/PDFCGui.jar" -Xmx1024m com.inet.pdfc.Startup "$@"
-Xmx must appear before com.inet.pdfc.Startup!
Open the /Applications/i-net PDFC.app/Contents/Info.plist with an appropriate editor.
Add for example -Xmx1024M under JVMOptions.
If you do not have an appropriate editor you can edit the file with a text editor and add the -Xmx as a value after the JVMOptions as follows
... <key>JVMOptions</key> <array> <string>-Xmx1024m</string> </array> ...