I'm experiencing a great amount of stuttering and lag with Ultima IX. Whenever I interact with an item, the narrator speaks, or when the character is entering a new zone (like leaving his house, or opening his gate), there's a distinct pause for a few seconds. If this happens when the narrator is speaking, his voice skips and loops.

I really don't know how to fix this. It is better once I set it to "fastest." Any ideas to help?

Also - how can I get this into windowed mode?

There isn't an in game way to make it window mode, an older topic has a few ways that might pull it off for you though:

https://www.gog.com/forum/ultima_series/ultima_ix_window_mode

No idea about the lag/stuttering.