Default placeholder background takes too long to display (FF ESR 38, Linux)

[dev-random]

When page contains too many blocked elements, my browser (Firefox ESR 38 on Linux) becomes extremely slow (each frame takes seconds to draw). It seems to be the result of combining linear-gradient and background-repeat in extensions.umatrix.placeholderBackground. Replacing the gradient with a data-uri-encoded png fixes the issue for me. Using -moz-repeated-linear-gradient instead of repeating the gradient with background-repeat works as well.

[Magister]

This is very annoing - scrolling is very slow because of this...
@dev-random did you managed to fix that locally? Now Firefox wants signed addons, so modifying it is not an option...

[dev-random]

@Magister

about:config

extensions.umatrix.placeholderBackground

url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAAAAACoWZBhAAAABGdBTUEAALGPC/xhBQAAAAJiS0dEAP+Hj8y/AAAAB3RJTUUH3wwIAAgyL/YaPAAAACJJREFUCFtjfMbOAAQ/gZiFnQPEBAEmGIMIJgtIL8QEgtoAIn4D/96X1KAAAAAldEVYdGRhdGU6Y3JlYXRlADIwMTUtMTItMDhUMDA6MDg6NTArMDM6MDAasuuJAAAAJXRFWHRkYXRlOm1vZGlmeQAyMDE1LTEyLTA4VDAwOjA4OjUwKzAzOjAwa+9TNQAAAABJRU5ErkJggg==") repeat scroll #fff

[Magister]

@dev-random Thanks a lot!

[ghost]

@dev-random

I've been waiting a long time for this too.
Thank you.

[jfrankenau]

I would love to see @dev-random's solution merged.