lets face it: OS X responsiveness needs to be improved. I'm not ranting about overall OS X performance, I've been using macs for many years on many machines alongside Windows, Linux and other systems, and for most purposes, I preferred the mac.
But there is one thing that has never really been improved since Mac OS X (it wasn't an issue on Mac OS 9): the time the system and/or applications need to respond to keyboard input or mouse clicks. Of course, there is always a reason why the system is busy. The network may be sluggish, an application is running in the background, memory may be at its limits, the hard drive might be fragmented (although it shouldn't) and so on. This is how the world is. Any system can be brought to its limits by such issues. BUT, on Mac OS X, when something isn't working as it should be, gui responsiveness is going down. This isn't the case on Windows, at least not to this degree! Let me give you two examples:
Displaying from the menu bar is not a complicated task for the system. However, when I click on the menu bar, it always takes some milliseconds until the submenu is displayed. Milliseconds aren't a big deal, but they are perceivable and my feeling is that they indicate that something isn't as it should be. If the system or the network or whatever is busy, these milliseconds may turn into seconds and this is not good.
Using a word processor (MS Word for most of the time, so you could indeed blame Bill Gates), I want immediate feedback when I am typing. On Windows, I get it. On Mac OS, when there are some background activities, it can happen that it takes 1 to 2 seconds until the characters I've typed are displayed. No character gets lost, so in case of no feedback, I can still go on typing, hoping that the text will appear sooner or later. But this is not how it should be. I guess this is the same sort of problem as the following one: when a browser, e.g. Safari, is busy opening a slow website, it may take some seconds to stop loading the page and typing in a new address.
I guess the reason for these problems lie deep in OS X architecture. A wild guess of mine is that it is somehow related to OS X's good overall latency. But when I am not using my mac on stage to play keyboard, but simply to work or to surf, I don't care about the latency of backgound processes, I simply want immediate feedback to my input (just as I get it on my windows machines). What about having the option to choose between "optimized for app latency" or "optimized for gui responsiveness" in the system preferences? Or is there another reason?