According to this comment https://github.com/archlinuxarm/PKGBUIL ... GBUILD#L10 LTO should be enabled for aarch64 in mesa. However, it isn't. Looks like it was removed in 06c1615cffa8e9b003b638dd2ee3c08d7382e6ad without any explanation.
Please either remove the comment or re-enable LTO for aarch64. The latter is preferred, as it's a double-digit percentage of performance increase in glmark2.
Is there a better way of reporting bugs than posting on this boomer forum from 2007?