Revert all symbols to objects macro?

no only on current  page

for all pages on active document try code below

Sub RevertSymbolsToObjects()
Dim sh As ShapeRange, s As Shape, dp As Page
ActiveDocument.BeginCommandGroup ("RevertToOjects")
For Each dp In ActiveDocument.Pages
dp.Activate
Set sh = ActivePage.Shapes.FindShapes(Type:=cdrSymbolShape)
For Each s In sh
s.Symbol.RevertToShapes
Next s
Next dp
ActiveDocument.EndCommandGroup
End Sub

This worked on a single page.

Was it still super-slow to process that one page?

If I might ask, how many pages does your document have?

88 pages. No it was fast. Only one symbol on this particular page. 

I would try it on a few more challenging pages.

You could "go for the gold" with an all-pages attempt:

Sub RevertSymbols_all_pages()

Dim p As Page
Dim s As Shape
Dim sr As ShapeRange
    
    On Error GoTo ErrHandler
    ActiveDocument.BeginCommandGroup "revert symbols all pages"
    EventsEnabled = False
    Optimization = True
    
    For Each p In ActiveDocument.Pages
        Set sr = p.Shapes.FindShapes(Query:="@type = 'symbol'")
            
        For Each s In sr.Shapes
            s.Symbol.RevertToShapes
        Next s
    Next p

ExitSub:
    Optimization = False
    EventsEnabled = True
    ActiveDocument.EndCommandGroup
    Exit Sub

ErrHandler:
    MsgBox "Error occurred: " & Err.Description
    Resume ExitSub
End Sub

Or, you could try to process just a subset of the document at one time with something like this:

Sub RevertSymbols_some_pages()

Dim lngPageIndex As Long
Dim p As Page
Dim s As Shape
Dim sr As ShapeRange
    
    On Error GoTo ErrHandler
    ActiveDocument.BeginCommandGroup "revert symbols some pages"
    EventsEnabled = False
    Optimization = True
    
    For lngPageIndex = 1 To 5
        Set p = ActiveDocument.Pages(lngPageIndex)
        Set sr = p.Shapes.FindShapes(Query:="@type = 'symbol'")
            
        For Each s In sr.Shapes
            s.Symbol.RevertToShapes
        Next s
    Next lngPageIndex

ExitSub:
    Optimization = False
    EventsEnabled = True
    ActiveDocument.EndCommandGroup
    Exit Sub

ErrHandler:
    MsgBox "Error occurred: " & Err.Description
    Resume ExitSub
End Sub

Sometimes you may run into a problem where some specific content gives CorelDRAW trouble.

Other times, you may have something where it works OK for doing a modest amount of work at one time, but cannot successfully process the whole document. One might even have to process part of it, then save the file and close / restart CorelDRAW before doing another part of it.

It took about 5 minutes to process 5 pages. There were maybe two symbols on any of those pages in total.

You can edit the line:

For lngPageIndex = 1 To 5

to process a different set of pages in the document.

That's a little bit painful, but it has the benefit that, if you have success, you can at least save your document and have part of the job done!

You might check, as you did earlier, to see if it's going crazy with memory use.

How complicated are the symbols?

Nothing crazy. Mostly hardware.

I guess I am wondering - even aside from automation - why the reverting of symbols to regular shapes is so slow.

Any chance that this is some of the nasty AMD video card / Windows 10 Creators Update performance problems some users have experienced with CorelDRAW?

I know that some of your information is proprietary. Could you share one of the symbols that takes ~5 minutes to revert?

If you create a new symbol - something simple - then is that also very slow to revert?