I thought that my camera was moving way too slowly after I increased the size to 6.5 million meters, so I increased its default speed. I also have a couple of keys that act as multipliers in order to get really high speeds. Unfortunately I realized that my terrain couldn't keep up with me because I was moving too fast. This is because the terrain would only move a maximum of 1 step each loop. So, if I traveled 3 steps' distance in one update loop, the terrain would fall 2 steps behind.
I wrote a solution to this by calculating the number of steps the camera has moved and then rotate the terrain the appropriate number of steps. This worked great and the terrain always kept up with the camera. BUT! Yes, the big dreaded but. The terrain randomly disappears. It will be fine for quite a while and then flash on and off like crazy. Even worse, sometimes it completely disappears and doesn't return, no matter which way I turn or move.
I have no idea what is causing this problem and I have tried debugging the code for awhile now. So either I find a fix to this bug, or I'll have to limit the speed to be slow enough that the terrain can keep up.
I feel bad for not having any media for so long, so here is a screenshot to appease the horde. I desperately need to get better texturing on the terrain, but that will come after I get the terrain working to my satisfaction.