I think ist is totale Levit for large ships to be was faster than small ones. That is simply the reality (remember we are in space).
When it Codes to acceleration and Turbine Speed however, big ships in Avorion are overpowered as ****.
If you are interested in additional thoughts about this, this topic might be interesting for you:
https://www.avorion.net/forum/index.php/topic,5420.0.html