And of course Flash requires a certain amount of compression/decompression of data which can be traced back to the hardware component, being the RAM. If your RAM is bad, Flash can get slower. Sometimes only by swapping known to spec RAM that is specific to that machine model with a lifetime warranty, will you finally get results. Apple's Hardware Test, Member, Rember, and other hardware tests can't detect all bad RAM. Unfortunately RAM tests even as they are done in the factory can't isolate all bad RAM. There isn't enough time in the age of the universe to completely test every possible conceivable RAM combination of circuits on any RAM board that is 16MB or more. And now we are dealing with GB RAM boards.
I guess most of my current complaints are related to a sloppy network in my office. I have to live with that. I suspect the network problems to be particularly problematic in combination with apple mail trying to synchronize.
I am really not complaining about overall latency. I really like OSX. I like to work with it. What makes me crazy is UI (and only UI related) latency. If the system is busy for whatever reason, I do not get any reaction to a mouse click for some hundred milliseconds, and this feels like the mouse button (or trackpad resp.) being broken. For example when I click on the window of an application that is in the background, it may take up to 2 seconds until anything happens at all. It is perfecty OK for this application to take 2 seconds to wake up. But in the meantime I'd like to see just some sort of reaction from the window manager (whatever it is called in OS X).
Probably my sensitivity is related to the fact that until recently my MacBook Pro had a hardware problem with the trackpad resulting in clicks occasionally not being triggered. So every time I did not get any feedback (be it due to trackpad problems or slow UI responsiveness), I alway asked myself: should I click again?
At least in part, apple is to be blamed (maybe it is fruitless to share this insight here, so I'll make it short), because I don't see why (while OSX is busy) I am able to instantly move the active window, while I don't get any feedback to other actions such as clicking on an inactive window. Sometimes, even clicking on the menubar takes quite some time.
Feedback towards user actions has a double edged sword in terms of design. Apple used to have many more "Appearance" Sounds that would give you feedback for every gesture of the operating system. They appear to have backed off from that, and I am thankful they did, because it was getting annoying to have to troubleshoot ghostly sounds coming from the computer for every little minor action, especially when someone's kid enabled it by accident. It still happens sometimes when someone's kid enables Universal Access by accident. Of course there will always be those who want an instant reaction from their every action to know they are actually doing something.
One design doesn't fit all sadly.