Microwindows/Nano-X Speed optimizations

[Ewan Meadows]

As I'm sure you have all noticed, PIXIL is pretty slow at the moment.
Here's a few things I've found that might speed things up.  I could do
with some kind of benchmarking program, as using the load monitor
probably isn't the best way to compare things!

You can turn on ERASEMOVE, which is found in the menuconfig menu's
under microwindows.  From user/microwindows/src/config:
# Window move algorithms for Microwindows
# Change for tradeoff between cpu speed and looks
# ERASEMOVE repaints only backgrounds while window dragging, quicker.
# Otherwise an XOR redraw is used for window moves only after button up,
# quickest (should set for ELKS)


I've tried enabling shared memory support, but unfortunately the
kernel we are using at the moment doesn't support it.  Apparently
versions >2.6.15 work, but this will require a major upgrade.

Also, is there any reason why we aren't using a preemptible kernel?

Cheers!