Background BT workers

Background workers (one for an image) are used to accelerate pages start up.

Workers off-line test

To test workers off-line use
security.fileuri.strict_origin_policy = false in Firefox
--allow-file-access --allow-file-access-from-files flags in Chrome.
I can't use workers off-line in mobile Chrome yet.

CSS pixels in Firefox

Firefox uses 1024 CSS pixels for my 1280 pixel screen. Then it scales fractal images 5/4 times. Therefore they are (5/4)2 = 1.5 times faster but a bit coarse. Use layout.css.devPixelsPerPx = 1.0 to set 100% scaling.

Workers performance tests

Sometimes workers are a little slower at start up than script without workers. But I get similar execution times, if I press the picture in the center (i.e. in the second pass). As I remember, I got similar results for Java JIT compiler.

updated 22 Oct 2013