The campaign fleet contains several battlecruiser types because they are built in batches and refitted when possible. That creates different performance groups even within the same broad ship category. Tactical units therefore group ships with similar speeds, avoiding a division in which faster hulls race around or the whole group is held to a slow formation speed. Fleet organization depends on compatible performance as well as the individual quality of each ship.
Notable Point · 3:34:22-3:35:16
Why tactical divisions need ships of similar speed
Batch-built and refitted battlecruisers are grouped by similar speed so a mixed division is not forced to maneuver at the pace of its slowest member.