If you've upgraded to Leopard and now find the IDE of the new Matlab release 2007b to be super-slow, create a file called java.opts in your /Applications » MATLAB_R2007b directory, and add the following line to it:
-Dapple.awt.graphics.UseQuartz=true
Then restart Matlab. This will switch Matlab back to using the Quartz drawing enginge (as it was in previous versions of OS X). Please find the original hint for this solution in this thread on the Mathworks Matlab forums.

