The beams of light are Waypoints accessible via the J key (always delete the death waypoints as soon as you've recovered your grave), and there is a setting in the Journeymap options to turn off those beams unless you are within a certain distance of the waypoint. If you don't change it, the default setting is infinite distance. When you have tens or hundreds of waypoints, those beams can fill the horizon, so you do need to lower that setting to something like 500 blocks.
I cannot play without the Journeymap mod installed, it is far, far, far, far too valuable of a mod to disable it. But we all have different play styles and opinions.
I think you can also selectively disable certain waypoints while keeping them listed, and only turn on the ones you need in that situation... At least I've seen LPs using it that way.