It isn't 35MH/s per 750ti (at least not mine) I think it is rather 26~28MH/s, also it could be some wallet issues, sometimes it gets stuck...
thanks for your answer.
re-checked - with the test windows system I find a block quite fast, without restarting the wallet.
And the hashrate is clearly not the same as in linux (linux = 35mhash per card vs. 25mhash with windows).
...here seems something wrong. does your miner has a debug mode (-dp)?