I have tested new Nvidia drivers against 347.00 drivers with same CPU & GPU settings.
Following differences are noticeable:
1. with 353.30 my GTX 960M in G551JW cannot run properly with MEM clock set to 1500 (3000). It must be slightly lower. With 347.00 - I can run 1500.
2. Overall performance of 353.30 is noticeably better, even with slower MEM clock (2970 instead of 3000):
Furmark - 2817 (was 2800).
3DMark Fire Strike - 4807 (was 4799).
Gain is stable. If I reinstall old drivers - results are back slower.
Also I did a test with old drivers, but lower MEM clock, just to be sure. It slows even more.
In Witcher 3 I can play HD, with graphics set to HIGH (but not uber, and no hairworks), textures to uber. It keeps stable 35-40 FPS, I have fixed frame rate to 30 FPS with Vsync on. Runs and looks nice.