As of libcairo2 1.10.2-6.1 and NVidia drivers 280.13.really.275.28-1 the slowdown doesn't occur anymore on my computer (I'm still using XOrg 1.10 because of the ABI v11 issues but this is a whole other matter).
It looks like NVidia added support for the missing server-side gradients functionality in 275.x, since the problem still appeared with libcairo2 1.10.2-6.1 and earlier NVidia drivers 270.x Can anyone confirm this so we can close this bug? -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org