Lamps have visual artifacts that increase in strength the further you are away from spawn. If I teleport to 100000 150 100000, lamps start having flickering halos and other visual artifacts. Tested on Latest Version of Forge and Project:Red.

Visible in my personal modpack and Direwolf20 1.6.4 FTB.

I can confirm this, I have glitchy lamps halo's at coords: +30000, 70, +65500.

Still happening on the 1.7.2 port.
Maybe it isn't fixable?

Related?: The lamp in the Creative tab for Lighting is causing graphical glitches with the next tab. The glitch disappears if you select the Lighting tab, but shifts to the next tab when the glitched tab is selected... maybe if a different block was used for an icon?

I'm going to say this is a minecraft related issue (at least in 1.7.2). At large coordinates
(10000000 100 10000000) some vanilla items render oddly. For example redstone dust appears magnified, the particles from torches are not aligned to the torch itself. In the latest snapshot (currently 14w25b) redstone is fixed (but torch particles are still out). When Forge updates (I believe they are planning for mc 1.7.10) I'll see if it is fixed.

In fact, to back up my last comment, the bug is on Mojang's side MC-3718
Once that gets resolved (and forge updates to resolved version) I hope this halo glitch will not occur.

Tested on minecraft 1.7.10, still occurs but not as bad for large (not huge) coordinates.

Just to confirm this is happening on the latest commit as of now.
Teleporting to 29000000 64 29000000 is really obvious and at such coordinates you can't see the halos on lanterns, fixtures etc.
There must be something in the code that renders halos according to x, y, and z values that breaks on large numbers

MC-3718 has just been marked as fixed for Minecraft 1.8, now we wait for the day when Project Red can be updated.

No point of keeping this open.

Might not quite be fixed: https://bugs.mojang.com/browse/MC-72562?jql=resolution%20%3D%20Unresolved%20AND%20reporter%20in%20(Battlefieldkille)