After all that, very sadly I have had to go back to the original Spacefox for now
Three things:
1.
Firstly, I needed to remove "twbt filesize 18 18" This seemed to conflict with the DFHack Mouse Query plugin, in which I use the track, live and drag options. Especially drag seemed to get confused - I think mouse query thought the cursor was at a different square than it actually was, such that when I dragged and then clicked, it jumped me back to where I dragged from. And if I dragged and then changed Z level down/back up, I wouldn't be at the location I last was, the location I dragged to. The end result was that trying to drag the screen with Mouse Query, it would keep jumping back to where I came from, or sometimes glitch up badly.
So I removed that from extra_dfhack_init.init, and things seemed fine again.
But then I started to notice:
2. My graphical FPS went way down with the new tileset. My init FPS limits are 100 CPU, and 40 graphical. I never get 100 CPU, the best I can get is about 40, and normally it's about 30. With the original Spacefox, CPU FPS and GFPS would always be the same, with CPU FPS being the limiting factor unless I was at >=40 FPS, then the GFPS cap would kick in.
With the new Spacefox Override, CPU FPS was still at 30-35, but GFPS was never higher than 25, and often as low as 20. Even with the game paused, Graphical FPS would hover around 27-28, while of course CPU FPS would go to the maximum.
Checking Task Manager, I could also see much higher CPU usage than normal. Normally I see it at 14%, which means 12.5% from one core maxed out (Quad core machine with Hyperthreading = shows as 8 CPUs, so 100% of one core = 12.% in total), and then about 1% of graphical CPU (I believe the game uses one thread for all calculations, and a second one for graphics?)
Using the new Spacefox, it was up to 19-20% total CPU. So I was using 100% of one core with DF CPU as usual, and then about 50-60% of another core on graphics, much higher than before. Though still not even 100% on the second, so I don't know why the graphics capped at 25-28 FPS when there was more CPU available. Inefficiency/bottlenecks in the graphics code, I guess.
In my init settings, I am using mode TWBT of course, and I don't have VSYNC (or the OpenGL method of VSYNC) enabled. I think the rest is pretty much at default.
Even that wasn't a huge problem; graphic updates were slower, but still quite playable, and I planned to try some tweaking eg that LINEAR/NEAR setting.
However, this *was* the end of the world:
3. My first ever crash in TWBT after 100+ hours of playing:I've only been playing properly with the new Spacefox Overrides for about 3 hours and then I got a crash, my first in TWBT ever after weeks of constant play, which surely can't be a coincidence
I've had a few other DF crashes, but I always check the Details and this is definitely the first in TWBT.
So I'm going to have to go back to original Spacefox for now. Very sad, because I really like the updated graphics.
I know almost nothing about DF graphics, but it seems to me most probable that it's the mixture of 24px and 16px tiles? At least that's something unusual/different/not expected maybe? Or is this done commonly by lots of tilesets?
Tomorrow I might see if I can make a new hybrid version, taking all the 16px tiles from the new Override but not using the 24px ones. That way I can at least still get the new walls and doors and fixed tracks etc. And I suppose I could even just do a basic resize on the 24x24, down to 16x16? Lose a little quality but probably wouldn't be that noticeable at the zoom level I use.
Or maybe it's nothing to do with 24px tiles specifically? I do use a lot of DFHack plugins, and I am using them constantly via shortcut keys. Including constant use of Mouse Query, which alters the UI. Maybe there's some instability there, which only shows up when TWBT/the graphics engine is working harder? I don't know. But I am certain it must have been triggered by the new overrides, as I've not done anything different tonight than I've been doing for the last 2-3 weeks of constant DF playing, all of which was with Spacefox.
Oh well, it's sad but not the end of the world - I still love original Spacefox! And at least now I've learnt a bit about tilesets and know how to make more changes for myself in future