Since the creation of line-move-partial, going to the next few lines
has become a P*TA.

I don't think my computer, with an Athlon XP 2000+, is too old to not
be concerned by Emacs user-friendliness :-)

With emacs -Q, if I entirely  fill the scratch buffer (150 columns, 75
lines) and then  press C-n and _stay on it_,[1]  the cursor is blocked
at the second line. When C-n is released, Emacs responds only after
a second or so.

If I remove the call to line-move-partial, everything is fine (except,
certainly, the display of partial images).

The guilty part seems to be this one:

    (let* ((ppos (posn-at-point))
	   (py (cdr (or (posn-actual-col-row ppos)
			(posn-col-row ppos))))
	   (vs (window-vscroll nil t))

Is there any solution ?

Footnotes: 
[1]  I use xset r rate 300 250, which is quite speedy.

----
In GNU Emacs 22.0.50.44 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2006-09-13 on mahaena
X server distributor `Gentoo (The X.Org Foundation 6.8.2, revision r6-0.1.13)', version 11.0.60802000
configured using `configure '--prefix=/usr' 'CFLAGS=-ggdb  -O0''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US
  locale-coding-system: iso-8859-1
  default-enable-multibyte-characters: t
----

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