Direct3D is a high-performance, COM-based API for accessing graphics hardware (GPUs) in a device-independent way on Microsoft platforms.
Graphics Device Interface (GDI) is a device-independent, pure software graphics API under the Windows operating system for drawing graphic primitives and text
So decide what you want to use direct3d is significaly faster than gdi
Should I use Direct3D or just Windows GDI for a fancy/high-perf Win32 app UI?
Imho the right way to go is direct3d or opengl but given delphi is windows only maybe direct3d is better;delphi was introduced exactly because the gdi is not good at such tasks
Delphi 6: Can native Delphi do smooth graphics like Flash?