Using the SLIMEY effect and flying with an elytra breaks the game. Not only do you go VERY FAST, but if you fly outside of the loaded chunks, the game lags a LOT.
VIDEO
Block Armor Version: 2.4.6
Other installed mods: Minecraft 1.12, Forge 14.22.0.2465
To reproduce:
Set 'armor pieces needed for effects' to 1
Make new world [creative mode]
Equip elytra and slime block leggings
Fly

Thanks for the report (and nice slimey reference)! This is fixed in v2.4.7:
BlockArmor-1.12-2.4.7.jar.zip