Hello guys...
My experience from years ago taught me full-screen DOSBox has a dramatically lower performance than the VGA-windowed. But that was years ago, I never again tried running DOSBox full-screen.
As my first purchase on this site, I was curious to see how GOG's black voodoo spellcasters dealt with this issue and, just like years ago, I was unimpressed with DOSBox performance playing Jagged alliance fullscreen. The game lags slightly sometimes, and many cutscenes have randomly blurry spaces, specially the "still" spaces (the sky or the ground for example).
So I was wondering how most people play it, if full-screen (which is the out-of-the-box standard from GOG) or windowed. Also, if you do play full-screen, do you have the same problems? If you did have such problems, what solution worked best for you?
I'm still testing it (have just installed it, couldn't actually play), and right now I'm using it windowed. It works for me quite well, the only thing that annoys me is that Windows Vista switches to "basic mode" or something, while the game is on.

weird, it runs flawless for me on fullscreen, i don't think i have any other GOG game that runs with DOSbox so i can't really compare, but it seems to run smoothly

i am playing JA2 1.13 in fullscreen in higher resolution w/o any problem, but I encountered what you have described with both fallouts, sometimes they are running ok and sometime laggish.

I'd suppose Fallout runs directly from Window XP/Vista without need of DOS emulation (Fallout 2 certainly does).
Anyway everyone seems to play only Jagged alliance 2 or later. I must be the only one still trying to beat the first game and never having played a campaign in the newer installments...