Been looking into this issue for a little bit, and just committed a new rendering method that will allow more control over the painting.
https://github.com//BLUI/commit/54e7fdfbaf9f39a76ec04706105efe171b2cee10
Eventually looking to only updating regions of the texture that have been redrawn by CEF.
EDIT: This has been merged into mater, as it seems to boost performance