Microsoft [https://docs.microsoft.com/en-us/windows/desktop/api/dwrite/ne-dwrite-dwrite_rendering_mode says this about] the difference between 4 and 5: 4 = DWRITE_RENDERING_MODE_NATURAL "Specifies that antialiasing is performed in the horizontal direction. This rendering mode allows glyphs to be positioned with subpixel precision and is therefore suitable for natural (i.e., resolution-independent) layout. The antialiasing may be either ClearType or grayscale depending on the text antialiasing mode." 5 = DWRITE_RENDERING_MODE_NATURAL_SYMMETRIC "Similar to natural mode except that antialiasing is performed in both the horizontal and vertical directions. This is typically used at larger sizes to make curves and diagonal lines look smoother. The antialiasing may be either ClearType or grayscale depending on the text antialiasing mode." But it sounds as though you are seeing something very different with 5 than you see with 4 (or -1, which I think defaults to NATURAL). What are you seeing?