Are you increasing the fan speed with SMC fan control? As pointed out, they do run hot. SMC will let you really crack up the fans. I use it when on mac side, and a similar tool when under bootcamp. They really get hot
under bootcamp as windows can't get to hardware level to control fans. This has been an issue since day one on the macbookpro and windows/bootcamp. Thank goodness for "speedfan" still works great.
I can't speak much to LR on the mac, but with Captureone7, once you start to process, you can watch the temp's climb and hear the fans kick on my 15". I tend to stay on the windows side for LR where it "she runs hot" as John Hiatt would say.
Since you are on Mac side, double check your SMC fan control settings. I have occasionally turned them back and not caught it.
Phil: One thought on the processor upgrade.
On your point, I would consider maxing your ram out. You are running great on the current processor, how much ram do you have. I just up'd my main box to 32GB from 16GB and with LR you do see some improvement, not
so on CS. LR seems to have better overall memory management. I am impressed that you are able to overclock that much and stay on air. You must have a big fan?
I am currently on a i7 3.4 not overclocked cooled by air and so far it's running great. 4 core 8 logical.