I like simple, fast, and responsive with my Amiga too. I think that is a big part of what makes the Amiga special. My Amiga is more responsive and doesn't slow down at times and over time like the 3GHz P4 XP machines I am forced to use all the time. That said, I use a 4000T, Cyberstorm MK3 '060, Mediator with Voodoo4, SFS and AmigaOS3.9 installed. This setup will make the standard glow icons in AmigaOS3.9 in 16 bit (~65k colors) *MUCH* faster than your AGA in 8 colors with FastFileSystem. There is no wait as the windows and icons appear with the biggest difference being SFS (and no CPU hungry IDE). I highly recommend SFS by the way if nothing else. Here's the link...
http://strohmayer.org/SFS of course supports >4GB hard drives that you need. Be sure to backup any important data from time to time as there is not many recovery programs available but they are rarely if ever needed.
P.S.
I purchased an E-Flash4000 (flash ROM) to get rid of the double reboot of AmigaOS 3.9, speed up the bootup, and get rid of many of the patches on top of the AmigaOS. Also MagicMenu and MagicWB will work fine with AmigaOS 3.9. It's good to keep an open mind and try new things with the Amiga. You might just be pleasantly surprised sometimes ;-).