Just figured I'd add my voice to those recommending the fan patch. It's great. I played MM1 before the latest DOSBox version was released and I had to lower the cycles considerably which made the whole game really slow. Then I found out about the patch, and it was awesome. I could raise the cycles back to normal and text was perfectly readable.
Also, remember that there's a text speed in the game options. In-game, you should set the speed to the slowest possible.
Finally, there are a few, rare instances when the text is still fast after using the patch. These are not very important... they are things like the message telling you that monsters have surprised you.... this will flash by and then you will be in battle. But it's not too hard to figure out what happened. All battle text and other text (like when talking to someone) is slow enough to read. Well actually I think when an enemy passes its turn (i.e. does nothing that turn in combat) that also goes by quickly. But again it's easy to tell what happened.