I think the main problem with the r_speeds is not the barrels, but the fact that the textures are scaled down so much. The brushes split based on texture units (one trick you can do to decrease r_speeds is to scale textures up). If you type gl_showtris 1, you can see how split up the map is.
Of course, re-making the barrels with 8-12 sides would help, too, but scale the textures up first and see what that does. The other problem with the scaled down textures is that the tiling looks really bad. You can see repeated patterns every few feet.
I'll go ahead and upload this to the beta server.