tdm_lg_split is an option split the lightgem calculation between alternate frames (eg. do half of the calculation in one frame and half in the other) as compared to tdm_lg_interleave which skips a number of frames for calculating the lightgem. The two cvars can be used together as they perform independent functions. It was reported in the past that tdm_lg_split caused flickering, mostly for particle effects. Since 2.03 introduced Soft Particles (also particles no longer render during lightgem processing) , this does not appear to be the case. Please confirm whether this setting (in Darkmod.cfg) causes flicker for you.
seta tdm_lg_split "1"
If we aren't seeing any problem reports, we should probably enable this by default in the next release.