Re: *fast* changing of LineColor?

After some suggestions from the answers of the to-quick-posted-post, i
now have the following solution:

void QGLDrawProgressiveRect(CDC* pDc, CRect& rc, COLORREF crStart,
COLORREF crEnd, bool fHorizontal) {
    register ULONG nMax;
    register ULONG nCnt;
    double dFak;
    LONG* pSlice1;
    LONG* pSlice2;
    LONG Slice0;

    CRect rcSlice = rc;
    HDC hdc = pDc->GetSafeHdc();
    if (hdc == 0) return;

    if (fHorizontal) {
        nMax = rc.right - rc.left;
        pSlice1 = &rcSlice.left;
        pSlice2 = &rcSlice.right;
        Slice0 = rc.left;
    } else {
        nMax = rc.bottom - rc.top;
        pSlice1 = &rcSlice.top;
        pSlice2 = &rcSlice.bottom;
        Slice0 = rc.top;
    }

    *pSlice1 = Slice0;
    *pSlice2 = Slice0;

    for (nCnt = 0; nCnt < nMax; nCnt++) {
        dFak = nCnt;
        dFak /= nMax;
        (*pSlice1)++;
        ::SetBkColor(hdc, ColorProgressive(crStart, crEnd, dFak));
        ::ExtTextOut(hdc, 0, 0, ETO_OPAQUE, &rcSlice, NULL, 0, NULL);
        *pSlice2 = *pSlice1;
    }
}

any ideas to make it still faster?