Hi those aprons are historically correct. However if you really want to disable them you need to make a mod.
In this mod you need to overwrite all the shield actors using aprons.
Sure a lot of the source files can be found on those very forums and more can be found on https://trac.wildfiregames.com/browser/art_source/trunk/art/meshes and animations
I assume you are not streaming, or using a chromecast ?
Did you try disabling vsync in the options (probably useless)
Do you have lag in the menu as well ?