Hi
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Thanks you for additional information. I tried to reproduce the problem with simple dummy document, but find and highlight process takes less than one second. Here is simple code I used for testing:
DateTime start = DateTime.Now;
doc.Range.Replace(new Regex(regexString, RegexOptions.IgnoreCase), new ReplaceEvaluator(ReplaceEvaluatorFindAndHighlight), true);
Console.WriteLine("find and highlight process takes {0} seconds", (DateTime.Now - start).TotalSeconds);
You can try to remove sensitive data from your document and attach it here for testing.
Best regards.