How to optimize line renderers?

I was using line renderers to draw the lines. But the performance of the line renderers was really bad since that I had a large number of line renderers. GL.Line seems like will only work in OnPostRender method that may not work in my case. I'm not sure.

Any methods that can optimise the line renderers or change to some other components which have better performance? Thanks.

==================================Update================================= Just tried to use GL.Line. It was slow as well.