You can equip whatever you want and you won't move any slower! The only slowdown occurring here is when the weapon is readied - and it's only a minor slowdown. The two settings I changed are the following:

fMoveEncumEffect
Default = 0.4000
New = 0.0000

fMoveEncumEffectNoWea
Default = 0.3000
New = 0.0000

I made this because moving around the world at a snail's pace is unbelievably obnoxious. It got so bad I stopped specializing in armors just so I could move faster. Of course, after playing through the game dozens of times the lack of speed becomes extra grating.