http://code.google.com/p/foxreplace/issues/detail?id=130

Large pages (or long substitution lists) can make FoxReplace either 
(1) complete but not with all substitutions executed
(2) hang indefinitely (while hogging resources) or
(3) crashing

To be fair, I am talking about a *huge* file and/or a *huge* substitution list. You can test the limits via the files at http://jo.koan.net/foxreplace (file names and explanation in the screenshot png should be enough but let me know if it does not make sense).

Am using FireFox 26.0