Hey there :) Trust me, I know testing ISA cards in PCI machines is "wrong". And that there are many reasons for this, but the bridges you mention are not, in themselves, the problem. I'd like to say "not all bridges are created alike", and also that the direct cpu-to-ISA thing has not been true since the 286 era. From anything 386 onwards there has always been a bridge of some kind involved. So yes, it's "wrong", but only in the sense that "there's a PCI bus here, wtf am I punishing myself with an ISA VGA?!?".

ISA performance can be "as good as it gets" on a PCI machine, and most BIOSes will allow you to configure it to a point that it can easily saturate the bus and even break stuff - just like in the good old days. Wait states and bus speed tuning being the most important things.

I also know that Tridents are not all garbage, but it is fair to say that the 9000-series (which is essentially a 8900C with some additional integration) isn't going to win any performance prizes no matter what machine you put it in. The 8900D on the other hand is quite impressive in DOS, keeping up with all but a small handful of much more expensive cards. It is, of course, useless for a GUI system since it has no acceleration functions, but for plain VGA it's pretty good.

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All that said, I have not made any attempt at tuning for speed in these tests, and as I'm sure came across in my post - this is a highly un-scientific test that is only meant to gauge the relative difference between those cards (and with room for failure even at that). Fact of the matter, and what I wanted to confirm, is that the Matrox is unbelievably slow; I'm fairly sure the original VGA implementation with discrete chips (rather than a "VGA chip") would've performed better. Hell, even UniVBE warns me when configuring it that the card is unbearably slow in DOS, and doesn't even expose more than 1MB in VGA mode, so I should not expect much from it. Well, I guess I confirmed that, at least. :D

The reason is, of course, that the Matrox is made for GUI applications. And in those, compared to its peers, it absolutely shines according to reviews at the time. I'm looking forward to testing it in a GUI environment, and I'll surely post about that somewhere as well. And I'll use more period-correct hardware, I promise! :)