I don't think it's about ship speed either, I think it's more about if Starmade process is busy to load things or not. Fact is when I tried and exploited T1053 (pictures above are from that test) my logs were flooded by errors and Starmade got difficulties to load sectors. I took severals screens to illustrate it and more than 90% of them were messy like that.
In comparaison, usually, when I idling with no big objects, no planets, asteroids around which could drop the fps and fills the process load, it's just reach 50% of failure for F5 and 5~15% failure F6 screens. Since that I assume if java process is busy, the screensave quality have more chance to be bad.