Improve performance of Search Replace in Word document using OLE and Delphi

After some experiments I ended up with the following code to perform Search and Replace in MSWord. This code works perfectly also in header and footer, including the cases in which header and/or footer are different for the first page or odd/even pages.

The problem is that I need to call MSWordSearchAndReplaceInAllDocumentParts for every string I replace, and I get an unacceptable performance (2 minutes for about 50 strings in a 4 pages doc word). Ideally it should be "instantaneous" of course.

Before handling headers and footers I was just doing search and replace in the main document (using wdSeekMainDocument). In that case the perofmrance was acceptable (even if quite slow). I just wonder why is it so slow: does switching view takes time? Typically headers or footers contain few words, so I expected that all the Search And Replace in headers and footers was not making the overall performance so worse. But this is not what I observed.

This is the code, at the bottom i put profiler results:

// global variable (just for convenience of posting to Stack Overflow)   
var
 aWordApp: OLEVariant; // global

// This is the function that is executed once per every  string I replace
function MSWordSearchAndReplaceInAllDocumentParts;
begin
    try
      iseekValue := aWordApp.ActiveWindow.ActivePane.View.SeekView;
      iViewType := aWordApp.ActiveWindow.ActivePane.View.Type;
      if iViewType <> wdPrintView then
        aWordApp.ActiveWindow.ActivePane.View.Type := wdPrintView;
      if aWordApp.ActiveDocument.PageSetup.OddAndEvenPagesHeaderFooter then
      begin
        Try
          aWordApp.ActiveWindow.ActivePane.View.SeekView := wdSeekEvenPagesFooter;
          SearchAndReplaceInADocumentPart;
        Except
            // do nothing ..it was not able to set above view
        end;
        Try
          aWordApp.ActiveWindow.ActivePane.View.SeekView := wdSeekEvenPagesHeader;
          SearchAndReplaceInADoc