Ignoring Perforce keywords when comparing revisions with Araxis Merge

In Araxis select View > Options
Select All Comparisons > Expressions and double-click an empty item to create new expression.

Type some description and paste this in Expression:
\$(Id|Header|Date|DateTime|Change|File|Revision|Author)(: .*)?\$

Select the check-box next to your new expression.

You may need to refresh the comparison results after this change. But it is persisted so you have to do it only once.
This can save lots of effort if you compare many files and most of the differences are in Perforce generated keywords.
BTW Perforce keywords are documented here - Using RCS Keywords

Enjoy!