If using K2 with Deadlock's Stacking Beltboxes and Compact loaders, the K2 Beltboxes speeds don't get update to match the new speeds.
Advanced Beltboxes (the tier above vanilla Express) has the same crafting speed as Express Betlboxes (which is 4) and Superior Beltboxes (the tier above Advanced) has crafting speed of 6.
This is a great mod btw!