Especially during the action sequences, the game is more or less unplayable.

I think that for dosbox games, ctrl F11 slows it down by 10 percent, and ctrl F12 speeds it up by 10 percent, if that helps.

Not helps because the game have serious issues with all the CPUs, even on Amiga.

That game always was very fast. Even back in the days.

DOSbox can change cpu cycles for speed. Ctrl+F11, Ctrl+F12
Someone said 2000 cycles was too much in a gameplay video.
going to try core=simple with 500 cycles instead of 1000. in dosbox_ns.conf under [cpu] entry

core = simple
cputype = normal
cycles = 500
cycleup = 10
cycledown = 20

Update: works well, can play inside fort level, cputype=normal plays good.