Debug renderer performance

[nitrocaster]

Debug render works extremely slow, have to be optimized.

[tamlin-mike]

See my comment in "Stuttering issue: I think I know the cause #131".

Once crossing a border, I got pretty much release-build framerates, in a debug-build, while previously they had been what felt like 2-4 FPS.

As noted in the referred pos, I have the savegame for it, and I plan to profile the hell out of it, but f you want a copy just holler.

[nitrocaster]

That's unrelated. Debug renderer is responsible for debug drawing, such as bullet trajectories, bones, pathfinding, covers, etc.

[Xottab-DUTY]

Superseded by #1687.