Since we last messaged, dosbox has released verion 0.70; I would recommend an upgrade. After doing that, change the following sections of your dosbox.conf:
If the game still is not fast enough, try setting cycles manually (start with perhaps cycles=16000) and make frameskip=2 (this you can change a little-- I am guessing you already know it just makes dosbox skip rendering two frames between each of the frames it displays).
If you have opengl working on your system (this requires closed source drivers) you might change output=surface to output=opengl. For me this caused a memory leak in dosbox 0.56, but they may have fixed it (or it may even be a problem related to my hardware/drivers).
by the way, are your alsa midi modules loaded? I see you mentioned not having midi. Something like (remember I use Debian and I forget what your distro uses)
You might have to look around to figure out which modules you need to get your midi working. Also, the default setting for the midi port may not work under linux. Under [midi] I got mine working partially
by setting it to config=128,0