The promised numbers on LTO and FIrefox http://hubicka.blogspot.ca/2014/04/l...2-firefox.html
LTO option sounds nice for release kernels of distributions (because generally you don't wanna wait hours for kernel to build while consuming a _lot_ of ram).
I tried building my custom kernel with LTO and it ate 3GB of ram (and my kernel is fairly slim - stripped of unneeded modules).
I dont think my 8gb of ram would suffice for allconfig, though patches seem to have mitigated ram usege to some extent (firefox LTO build takes 7gigs easily on 64bit).
BTW, I have noticed on Jan Hubicka's blog that LTO brings most benefits when used with aggressive optimisations like -O3 and profiling driven optimisation.
So it would be nice to have that option with kernel, too. If it wouldn't break anything.