I propose that we build all packages with LTO by default which will provide better performance and reduced package size at the cost of slightly longer package build times. The size decrease is not massive, but it will surely make a difference.
Not all packages will build with LTO (for example libwebkit-gtk and for some languages) but it should be a good candidate as a default option. I suggest adding a bool in package.yml for turning off the LTO.
OpenSUSE have recently switched over to building all packages using LTO in Tumbleweed, see here for more info.