Try turning off the screen writes (Important: remember to turn them back on)

    Docmd.Echo False
    DoCmd.OutputTo acOutputReport, "ManAnnualDetailR", acFormatPDF, OutputFile
    DoEvents
    Docmd.Echo True

Kevin, my hero

It worked like a charm

many thanks

You're welcome.

I don't think DoCmd.OutputTo causes the slow screen update, because it doesn't actually opens the report.  It is DoCmd.OpenReport that  opens the report in whatever screen mode you specified.  If the report's record source is slow in retrieving the data, the screen will naturally be slow in updating -- the same thing that would happen if you open the report manually yourself in the navigation pane.  You need to speed up your record source, such as by using temporary tables (as per my suggestion a few days ago).  Or simply remove DoCmd.OpenReport.  Your users don't really need to see the report.  They only need to see the PDF, which can be opened with  DoCmd.OutputTo if you set the option after the file name to True:

     DoCmd.OutputTo acOutputReport, "MyReport", acFormatPDF, "C:\My Documents\MyReport.PDF", True

Kevin Yip my friend
you are always full of great ideas. In my user's case, the printed report is their primary interest. the PDF is only required by the few. Having said that, I will be implementing your temporary tables method to all my reports.

Have you had the chance to look at my post for opening a back-end database to manipulator the tables? The link is below.

https://599cd.com/blog/display-article.asp?ID=1953&CommentID=76694#StartOfComments

I would love your input on that.

Many thanks