Currently only brings four new features:
- forcemodels, with seamless fixing of tag indexes, and clientside animation frame fallback
- clientside player model LOD, reducing LOD when fps are low to help cl_minfps
- saves a BIT of bandwidth, not much
- saves some server CPU time (no more customizeentityforclient on player entities)
Currently can be turned off by sv_use_csqc_players 0, to help 0.5 clients which don't support this new code properly yet (they will get no prediction).