Did you render the clip by hitting the Enter key on your keyboard?
yes rendering should help, also let us know your media type and Project preset.
Try to increase the font size.
I think that Rendering will help, per your description. Along with that, also be aware that one can NOT use the Rolling Preset, and instead use the fixed Effect>Motion>Position and Keyframe that as an animation. You will still need to Render for smooth playback (Rendering is only for smooth playback). With Keyframing, you can "pause" the Roll, and have it come in, and go out, at different speeds. So very much control.