So cool to find this forum and see that I'm not alone!
I've just ran IRIX 6.5.22 under MAME 0.264 today for the first time on an AMD Ryzen 7 PRO 7840U laptop and managed to make it run REALLY fast, in fact, MAME says 70%. It boots in a relatively short amount of time, launches simple apps like the terminal pretty quickly and gives an almost lag-free feel to using this terminal and running simple commands in it like top, or an editor like vim, etc. A pleasure to use!
I used the following as a base, and managed to get it up and running in less than a few minutes:
https://drive.google.com/drive/folders/1...CmwuowfYDG
At first it ran pretty slowly and was very laggy, which I thought was to be expected, but then after I gave it more RAM I managed to make it run at ~70%.
The trick was to make sure MAME gives it more RAM, more specifically, 128MB instead of the default 16MB. You do this by pressing the Insert key on your keyboard, then the tab key to pop up the MAME menu, and under "Machine Configuration", in RAM Bank A you set it to use "4x32M". I did have stability problems when trying more RAM via bank B, so just stick with 128MB via Bank A for now.
All in all I'm super impressed, and very happy with the result. Since the current MAME driver for an emulated Indy does not use more than one CPU core on the host, the speed from or over the original hardware you will reach highly depends on the single core performance your machine will have. That said, I'm fairly certain that something like a late generation Apple M3, or the M4 that's about to be released shortly could run it at 100% speed, or faster.
Unfortunately I only managed to get networking to partially function so far.