'Bout had it with SD & iMac...

As I stated in another problem post, my SD2 Pro & me have been getting along since Christmas.  Recently got a new iMac 27 - real PIA machine.  D/L & installed Repetier 0.56 for Mac.  After a couple of days, I finally got some response from the SD.  I think I have all the settings correct, or close.  The manner of loading an STL file is different, got that figured out.  Still can't watch the bed & extruder temps come up to settings, but I found a way around that.  Finally got it to respond to the X - Y - Z movement commands - but SLOW!! Takes near 12 - 15 seconds to transverse the 150mm X axis, same for the Y axis.  Loaded a small STL file and set it to print.  A snail can move quicker, and although it seemed to go through the motions, it didn't extrude a drop! 
Quit it all, plugged the SD back into Win 7 with Repetier 8 and printed the test file at normal speed. 
Just spent an exorbitant amount of $ on this Mac, and would really like the Mac & SD see eye to eye.....

Any help would be appreciated....

Thanx
Ski