property SmoothScroll: Boolean;
When SmoothScroll is True, non-thumb scrollbar commands such as line up/down and page up/down animate toward their target offset in short timer-driven segments instead of jumping in one paint pass.
Dragging the scrollbar thumb still tracks immediately so users can scrub large documents without waiting for animation catch-up.
All TPdfView display properties trigger a repaint when assigned; you can change several in sequence without flicker because the redraw is coalesced into a single invalidation.
Active := True.SmoothScroll is view-local; replacing PdfView1.Pdf does not copy view-only settings from the old component relationship.
begin
PdfView1.SmoothScroll := {value};
PdfView1.Active := True;
end;