The Rule is draw everything in a single call to Drawprimitives

Drawing many lines will eat ups your framerates, so I guess the
rule is draw everthing in a single call to Draw????Primitves as
much as possible, ah and PrimitiveType.LineList comes in handy
for drawing lines using two vertex of VertexPositionColor type.

Collate them all and store it in a VertexPositionColor collection
list then draw it in a single call using DrawPrimitives with
PrimitiveType.LineList.

:))