How slow is a G4 compared to a G5 ?

The loan period is nearly up for the dual G5 Apple are lending me (they only loan them for four months and then sell them on). So it looks like they will be replacing it for another loaner soon.

The dual G5 is lovely, obviously, but it is pain to move around (and I expect to be moving it between home and the customer's site a bit soon). So I was thinking of asking for something smaller than the dual G5/Apple Cinema display option.

I was thinking of asking them for a Mac mini instead. How much slower is that going to be ?

The dual G5 has two 2.5Ghz processors, but I have yet to find any task that feels any quicker on the Mac than my 1.4Ghz Pentium-M laptop (I don't have a copy of Photoshop for the Mac ).

How much slower is a G4 compared to a G5 of the same clock speed ?

I remember how horribly slow low spec Macs were back in the days of System 7.x, so I am worried that the Mac mini is going to feel very slow.

I'm not doing anything particularly taxing with it: Xcode, Director, bit of web browsing. I'll make sure it has 512Mb of ram.

The mini is basically a laptop without the screen, keyboard/touchpad or battery. It's faster than my TiBook was but slower than my AlBook is. I find it perfectly reasonable to develop software on, but I'm told using the mini for midi and dealing with I believe it was 8 tracks simultaneously real-time will top out the CPU. I have not confirmed it.

what about using the mini for video editing and DVD authoring?

You can do it, but it won't be as nice as working with a really fast G5 with gobs of memory and a really fast video card. As Apple's applications start to take further advantage of 3D acceleration hardware, the difference will be even more apparent. It's already impossible to run Motion on a config as lowly as the Mini.

Bruno