probably wrong section, but I hope I can help.
Try editing file Dosbox.conf using your notepad (create a backup first, to be sure). Check what you have in:
Default is 10, and this is the number of cycles you increase by pressing Ctrl-F12. Probably this value is too low and you cannot see any speed increase. I had this issue when I played Alone in the Dark 2. Try changing it to a much higher value and see what happens when you use Ctrl-F12. Just experiment a bit.
If you want to get back exactly to the previous cycle value, also check:
This should have the same value of cycleup, so you can get back pressing Ctrl-F11 once.
You should also try checking the line:
By default is "auto", but you can also try finding a better solution by using the following:
where xxx is the number of cycles you want at startup. Experimenting a bit, you can find a good cycle value. I never used cycleup and cycledown with cycles=auto so I am not sure if this can also be a problem. You can try for example
and see if this is ok, too fast or too slow.