Daniel Vetter writes:

Just a quick comment on this: Since most framebuffers are write-combining,
and reads from that tend to be ~3 orders of magnitude slower than writes
(at least on the pile of machines I looked at here, there's big
differences, and some special streaming cpu instructions to make the
reading side not so slow).

So scrolling by copying tends to be significantly slower than just
redrawing everything.

I know this was the case years ago with AGP as iirc, it doubled ( 4x, 8x
) the PCI clock rate but only for writes wasn't it?  I thought this was
no longer an issue with PCIe, but if it is, then I guess I'll go ahead
with cleaning up the dead code and having it re-render with the larger
text buffer.