@Rob
The other day I was trying to do an install of Arch on my AMD netbook, however I found that the default linux 45 kernel tends to get my cpu stuck. I get that funny error "CPU 1 stuck for 22 seconds" every few seconds, so I'm not even able to execute the most basic commands and get my build up and running. This got me curious because the last time I tried linux 45 on my Manjaro install a few weeks ago the cpus had very high load and everything was stuttering. I'm no expert but if I remember well you were planning on acquiring some low power AMD hardware for mobility some time ago, so maybe you had a chance of looking into what's specifically causing this within linux 45 on some of these machines? It seems like there also other Arch users reporting similar issues under similar circumstances.