Before 1.9, I ran multiplayer with all settings on 'High' and of course, no DX11 nor enhanced textures. After I installed the DX11 and 1.9 with texture pack, I turned everything on and all settings to 'Ultra' and I did notice a good amount of performance drop in singleplayer. But when I went to multiplayer, I turned everything off and put all settings back on 'High' as before. However, I now have a pleasant increase in performance on multiplayer. Before 1.9, multiplayer ran at an average of 40-50 FPS and sometimes dipping to the low 30s or maybe high 20s, randomly, believe it or not. Now when I play multiplayer, after 1.9, with the same settings as before, I run a constant 60-70 FPS and the game never dips below 40 FPS.
I'd say Crytek didn't just add support for DX11 and textures with the 1.9 patch, they seem to have optimized the DX9 performance quite well.
But am I the only one that is seeing a benefit in performance after 1.9? Remember that this performance increase was shown when running the game at the same settings as it was before 1.9, which means without DX11 and enhanced textures.
I'm running dual HD5850s and 8GB of RAM just FYI.