Yeah I did apply bootanimation , and there's only one kernel available that works with my rom which is this one : http://xdaforums.com/showthread.php?t=2568479 , in a modified version (because this exact one from this thread causes SystemUI to constantly crash on boot in recent versions of CM 12.1) and it's supplied by default with the rom
I'll try to get safemode to work (doesn't seem to be working for me, and it rebuilds the friggin Dalvik cache everytime it reboots which takes ages.. pretty damn annoying) and see if I can disable the theme and try applying it one by one then
Thanks again for your help
Yeah, that sounds like the kernel issue, some kernels react poorly with themes on the latest update of CM12.1 roms.
The only on my end was to flash a new kernel on my Nexus 6 to fix this issue.