[cairo] odd line widths are slow

[Cliff Brake]

Hello,

We are running the following setup:

- PXA270 ARM CPU (520MHz)
- xserver-kdrive-fbdev (1.4.0)
- Cairo 1.8.8
- libpixman: 0.17.1

What we are finding is cairo line widths (cairo_set_line_width) that
are even numbers (2.0, 4.0) perform reasonably well.  When we set the
line width to 1.0, 3.0 or some odd number, the Xwindows CPU
utilization goes from 10% to around 50% in the system.  So for some
reason odd line widths drastically reduce our app performance.

Does anyone have any idea why this might be?

Thanks,
Cliff