9.1 Proposal: Top five performance problems

[Marco Pesenti Gritti]

Problems and ideas in no particular order.

* Sugar shell startup is too slow.

Reduce dependencies, single process shell, modularize and delay
initialization of components which are not immediately necessary,
measure constantly to avoid regressions and monitor progress.

* Icons rendering is slow and uses too much memory.

Cache svg icon on disk pre-rendered and mmap them, render colored
icons using a mask per color, user server side pixmaps to speed up
rendering of some of the icons.

* Activity startup is ridiculously slow.

Design an API incompatible Activity class. Start from a very basic
window and add functionalities on the top of it, trying to not regress
startup time. Make sure that launcher feedback does not slow down
startup.

* Browse performance and memory usage.

Investigation to do here. I'm hoping to have more concrete data by the 17 Nov.

* The frame is too slow to appear and disappear.

Experiment with pixmap caching. Is an empty frame fast enough?
Composite the active window and the frame.