Has anyone else experienced this? I'm pretty bummed right now, I spent a couple hours generating maps to get the sorta combo i wanted, finally got it, and now I have the issues in the title.
I literally embark on the spot I want, and for about a minute, being a new map, my framerate in game runs at 100 (the cap it's currently set at in the init file). However, after that minute, everything just takes a dive. The framerate bombs south to, literally, 3. All I did was dig a couple stairways down into the soil (to level 5), and on the first underground level, queued up the digging of 6 9x9 rooms. Nothing complicated or weird. Something I've done a dozen times now at the start of an embark. I've never experienced anything like this though. After about 2 or 3 minutes of that, it rises back to about 30 fps, then so far it's just stayed there (haven't played through the first season yet, just FYI).
There is a stream running through the map, and it has 3 biomes...two joyous wilds ones, and one terrifying biome. Early spring on this map starts with a snow storm blowing on most of the map, with the northeast corner (one of the joyous wild biomes), being green and having no snow on it.
Could it be the river, and the ice/water calculations? Could it be the weather calculations, especially with the weird northeast biome not being snow covered or, seemingly, involved in a snow storm that the rest of the map is getting?
It's just bizarre, I can see no reason for a massive dive in framerate in the begining of the game. I'm not an experienced player, like I said, I've only had maybe a dozen embarks, but my previous, fairly large fortress, with a full 200 population and many sublayers of rooms ran better than this. I mention my newness only as a reminder to be careful about any possible spoilers you might throw out there.