Crashes during world gen greater than 257x257 tend to happen during the lake generation/drainage portion, I've had it complete the hundreds of passes only to freeze in that moment and the program will usually eventually close, so I can't even interrupt it to view what was created, though there are times I believe I have closed it myself, so I could probably let it run over night. I probably haven't done this enough times to be sure. I'm trying to remember, but I feel like I may have interrupted a 1025 attempt, but the world was mostly mountains and I was unable to get it to work again, but maybe I'm thinking of one of the 513 attempts. All of my attempts over 1025 failed.
As far as I know when I last glanced at performance stats, I haven't run out of memory yet. I have a pretty high end consumer system for modern gaming (i9 9900k CPU) and no component appears to be maxed or failing during world gen, the program itself just hangs and that's only beyond the size limits, so I figured I was just "breaking" the generation algorithms and could figure out which variables to change to what values might allow it to get to the next step. For fortress mode , I don't know when I'm going to experience gameFPS death, but I have had some moments at around 125 dwarves where during a Civ Alert it can chug hard briefly - I can manage this with burrows and I'm sure other ways, but I haven't quite dug into that yet, oh, pun intended. I'm sort of new to this game, but not games like it, I just haven known of it for awhile and tried Adventure mode back awhile back since I've played old school roguelikes, so my experience on different topics is kind of all over the place. I have a STEM background, do a lot of gaming (ha), but very little programming, so this probably limits my ability quite a bit, the whole memory editing and trying to figure out how to trace a route to easily edit what I need to consistently was going to take me awhile to figure out, if at all.
Cancellation spam will straight up drop me to single digits, but that was easily fixed by temporarily disabling the announcements. My single thread speed and cache is up there, but I'm pretty sure my experience won't be much different from most users overall after seeing gameFPS drop under certain conditions and zooming out will drop FPS to single digits as well, no reason to play like that of course, just an observation. I don't think this a problem that you can just throw expensive hardware at, I just happen to be an enthusiast when it comes to gaming, though this was a rare move for me since in the past I went with more cost efficient hardware. Pretty sure my dreams of setting an absurdly high population cap will be crushed long before being even close to reached, if I even make it there of course. I mostly understand the rules and limits of the game and what's out there, but not
totally and I can still easily mess up even though when it comes to games like this I am often careful and deliberate.
I have tried cancelling history mid generation, but yeah, the last times that I tried, it just doesn't get there. I haven't really had the motivation to try again yet, I still need to look into how I would do this with the GUI/GM because I really am not savvy when it comes to scripting, or at least it takes me awhile to dig though. Quick example was I was really interested in Dwarf Therapist's scripting, but couldn't find a reference library and it seemed like it was designed for someone with an intuitive knowledge of it, so I set it aside for now since I assumed I was just missing something that would be otherwise obvious to someone familiar. Specifically I wanted to call all the dwarves who had picks in their inventory, and it looks like you can do it, but maybe I'm over estimating what that program can do, I don't know. Pretty sure I just needed the item codes and then figure out the command structure to write to do that, but yeah, I'm already getting into the part where I need to look a lot of stuff up and trial and error.
Edit: I should also add, although I noticed the oversized world gen would often hang before steps completed, if those steps completed at all, but there were times where they did not hang at all and actually ran quite quickly, up to where it would crash of course. I suppose I should make sure to try those seeds multiple times to be sure, but I think that might be a key indicator that the program likes the values and then work back and forth from those values depending on results.
Edit 2: I just did another quick look though of this
https://dfhack.readthedocs.io/en/stable/docs/Plugins.html#map-modification , if I am in the right area, went through that page's side bar and some of the definitions listed from other sections, and I'm just not seeing world size. Maybe I just need to keep reading up on it.