I've read this mac support forums, and found that many users(no offence) has no clue what mac os is. So to prevent future standart questions ill try to answer some of them here
Q)My game doesnt starts, what to do?
A)First of all check if you have Mac os system at least Lion or Mountain Lion. If you dont go to app store and upgrade to latest one(it costs ~30 bucks).
Before updating check how old your mac is. If mac older then 2 years i'd recommend you to update to lion, otherwise to mountain lion, because some changes were made to graphic user interface, so it using more resources to display itself.
If you have Lion/Mountain Lion, but game still doesnt starts, check if your mac is good enought to run Lotro. If you've played on windows using bootcamp/paralels/crossover/wine but cant play using native mac client, remember that bootcamp using Direct3D to render Lotro, wine/crossover using self written opengl drivers. That means you need at least Nvidia 8+ series(exclude gpus like 8400m, 8500m, 9400m, 9500m, gt210m, gt220m because these gpus were developed for office-kind software) and amd 4000+series Also if you have Intel built in graphics, you most likely wont be able to run game with enough fps to play smooth. Always put your lotro client into YOURHD/Applications/. In some cases some symbols from 'username' can play bad joke with config files of different applications.
Q)I have my client running, but i have very low fps
A)First of all check what mac do you have, then go to apple site and check its specs. If you found that your graphic card in list above(excluding those, which i mentioned as office ones) then go to preferences and start lowering your options. Always start from Antialiasing, turn it down, then shadows and post-processing. NExt step will be resolution. SOme old Imacs have pretty big resolutions with low-end graphic cards(like ATI Radeon 4670) which will result to low fps on high resolutions. If nothing above helped you, go to system monitor and check if any application using huge amounts of cpu time or RAM. Remember to run game with at least 30fps you need 2+GB of free RAM(more better). IF you have SSD in your mac, make sure you move client there. The last option for your low fps(if you have nvidia) its download official nvidia drivers from nvidia.com. The most sure and most risky way will be to hard upgrade your gpu. There are possible way that your new gpu wont be work as intended due to bad/non existant drivers, but there are some gpus, that are native for more new macs. Check specs of new mac Pro on apple website, and then buy same from some local hardware reseller. ATTENTION: if you buy new gpu, its totally your responsibility and you doing it on your own risk.
To be continued.
Ps if you've encountered some bug(non gameplay related), post it here and i will try to find fix for it