Exporting a range of pages (with an SDE data source) is slower in ArcGIS Pro than in ArcMap.

Workaround

Export the page range via ArcPy (Python) instead.

Use the following code to export:

##Export Page Range Map Series to PDF

aprx = arcpy.mp.ArcGISProject("CURRENT")

lyt = aprx.listLayouts()[0]

ms = lyt.mapSeries

start = time.time()

ms.exportToPDF(f"C:\Temp\{lyt.name}.pdf", "RANGE", "1-10", resolution=300)

end = time.time()

print(f"{lyt.name} exported in {end - start} seconds")

print("Done")

Steps to Reproduce