How have people been benchmarking their applications to determine what the hotspots and know where to optimize? Personally I’m currently using OptimizeIT for code coverage and performance hot spots. Are other people actively optimizing their applications for algorithmic issues or relying on the JIT and/or gcj and the like?
I use Optimizeit which came with JBuilder Enterprise. Nice tool but I only resort to it when I notice an issue with speed. If the speed is “good enough” I dont waste the time :).
To optimize my code, first i use a profiler to see what part of the code is mostly called, then i make little speed test (using System.currentTimeMillis())…
-Xprof for me. That, and a bit of weasly cunning, like my hunch with floating point.
Cas 
I tend to logically deduce where the problem is likely to be, then binary-search the method stack with System.currentTimeMillis() or the LWJGL high-res timer.
It means a lot of recompiles and re-runs, but I fair tear through them so it’s no time-waster.
I intend to get a profiler/debugger at some point and learn to use it, just haven’t been bothered enough to yet. ;D