I am using the following macro to insert a mini table of contents between two identical heading styles (e.g. Heading 1). It works fine on small documents, but is very slow on large documents.Sub MiniTOCFields(HeadingNumber As Long, TOCLevel As Long)  ' Add mini TOC fields after all occurrences of a Heading style.  ' HeadingNumber defines which heading style to add miniTOCs to (e.g. Heading 1).  ' TOCLevel defines to what heading level the TOC shows (e.g. down to Heading 3). Dim bookmarkNumber As Long  Dim bookmarkRange As Range  Dim insertRange As Range  Dim currentParagraph As Paragraph  Dim paragraphNumber As Long  Dim currentTOC As TableOfContents  bookmarkNumber = 0  paragraphNumber = 0  Set bookmarkRange = ActiveDocument.Paragraphs(1).Range' Cycle through each paragraphFor Each currentParagraph In ActiveDocument.Paragraphs     paragraphNumber = paragraphNumber + 1     ' Check for occurrences of Heading X     If currentParagraph.Style = Heading  & HeadingNumber Then         ' If this is not the first occurrence, create a bookmark between this and the last one         If bookmarkNumber > 0 Then             ' Move the end of the bookmark to the end of the next paragraph             bookmarkRange.End = ActiveDocument.Paragraphs(paragraphNumber - 1).Range.End             ' Create bookmark             ActiveDocument.Bookmarks.Add _                 Name:=TOCHeading & HeadingNumber & _ & bookmarkNumber, _                 Range:=bookmarkRange         End If     ' Move the start of the bookmark to the beginning of the next paragraph     bookmarkRange.Start = ActiveDocument.Paragraphs(paragraphNumber + 1).Range.Start     ' Add the TOC field              Set insertRange = currentParagraph.Range     insertRange.Collapse direction:=wdCollapseEnd     ' Add the new TOC field     ActiveDocument.Fields.Add _         Range:=insertRange, _         Type:=wdFieldEmpty, _         Text:= TOC \h \o  & HeadingNumber & - & TOCLevel &  \b TOCHeading & HeadingNumber & _ & (bookmarkNumber + 1)     bookmarkNumber = bookmarkNumber + 1 End If    ' Check for last paragraph and bookmark    If paragraphNumber = ActiveDocument.Paragraphs.Count Then        ' Move the end of the bookmark to the end of this paragraph        bookmarkRange.End = currentParagraph.Range.End        ' Create bookmark        ActiveDocument.Bookmarks.Add _            Name:=TOCHeading & HeadingNumber & _ & bookmarkNumber, _            Range:=bookmarkRange        bookmarkNumber = bookmarkNumber + 1     End IfNext currentParagraph' Update all TOC fields in documentFor Each currentTOC In ActiveDocument.TablesOfContents     currentTOC.Range.Select     currentTOC.UpdateNext currentTOCEnd Sub
Macro for inserting a mini table between heading styles
performance;vba;ms word
Optimization:You've done a good job of making sure you're not processing more than you have to, but there are a couple of things you can do here to improve performance. Instead of looping through all of the MiniTOCs you've just inserted, updating each one individually. Just update all of the fields in the entire document at once.Replace This:' Update all TOC fields in documentFor Each currentTOC In ActiveDocument.TablesOfContents     currentTOC.Range.Select     currentTOC.UpdateNext currentTOCWith This:ActiveDocument.Fields.UpdateIt also turns out that there's no reason to  to check every paragraph's style. We can find them all. Below is the uber simplified logic that you would need to implement. Also note that subs/functions should have a verb-noun type name. I changed it in my example.Private Sub test()    InsertMiniTOCFields wdStyleHeading1, 3End SubPublic Sub InsertMiniTOCFields(headingStyle As WdBuiltinStyle, TOClevel As Long)    Dim bookmarkRange As Range    Dim bookmarkNumber As Long    Dim currentRange As Range    Dim insertRange As Range    Dim doc As Document    Set doc = ActiveDocument    Set currentRange = doc.Range 'start with the whole doc as the current range    With currentRange.Find        .Forward = True         'move forward only        .Style = headingStyle   'the style given as an argument        .Execute                'update currentRange to next found instance        Do While .Found            ' code to insert bookmarks            ' Add the TOC field            Set insertRange = currentRange 'I changed this assignment from currentParagraph to currentRange            insertRange.Collapse direction:=wdCollapseEnd            ' Add the new TOC field            doc.Fields.Add _                Range:=insertRange, _                Type:=wdFieldEmpty, _                Text:= TOC \h \o  & HeadingNumber & - & TOClevel &  \b TOCHeading & HeadingNumber & _ & (bookmarkNumber + 1)                bookmarkNumber = bookmarkNumber + 1            ' update currentRange to next found instance            .Execute        Loop    End With    'update all newly inserted MiniTOCs    doc.Fields.UpdateEnd SubYou can also turn screen updating off to pick up some more performance. You will need to introduce some error handling into your code if you decide to do that though. You'll want to make sure that screen updating is always turned back on when your sub exits; even if it errors. Truthfully, I imagine that this routine should really have an error handler anyway. Here is a pretty good error handling pattern to follow.Other Notes:You really shouldn't access the document with ActiveDocument each time. It's much better to store the reference in a variable. This way, you know for a fact that the document you started working on is the one you'll continue to work on.Dim doc as DocumentSet doc = ActiveDocumentWatch your line indentation. Ends should be at the same indentationlevel as the If they belong to.Instead of declaring HeadingNumber as a long in your subdeclaration, you should consider using WdBuiltInStyle.So instead of this:Sub MiniTOCFields(HeadingNumber As Long, TOCLevel As Long)      '......    ' Check for occurrences of Heading X     If currentParagraph.Style = Heading  & HeadingNumber ThenYou would have this:Sub MiniTOCFields(headingStyle As WdBuiltInStyle, TOCLevel As Long)      '......    ' Check for occurrences of Heading X     If currentParagraph.Style = headingStyle ThenYou write pretty clean code. I like your variable names. Very concise and easily understandable. You use line continuations judiciously, but it can be a slippery slope. Be careful with that.