Cubase 7.5 real time spiking

My realtime cpu keeps spiking in cubase 7.5(latest update installed), this only started a few days ago, I have an I5 with 16 gb mem running windows 7 64 bit, its running a m audio delta 1010 soundcard, I only have a few vsti’s running with a few audio tracks and my system is incapable of running this at present, if i take off asio guard and multi processing it runs better, however if I switch to a completed project, with the current config it wont run, The finished project has around 70 tracks all running plugs and vsti and 3 weeks ago was running flawlessly, I’ve switch to a tb3 to use as a soundcard thinking my delta card might be at fault and it runs a bit better but still the same results tbh, I’ve checked the core temp of the cpu and its running at intel’s safe temp (35 degrees) I seem to think its an issue with Asio, so I updated those drivers too but no change, This is my job and not just a hobby so I had to revert back to cubase 7(my orig purchase) to get through a mountain of mounting studio jobs in the hope that it would run better and guess what, my system runs without error in Cubase 7 running the exact same project which I find very confusing lol, however it does tell me that the hardware config on the system has no issues if 7 can run smoothly, I’ve re installed Cubase 7.5 twice, and updated to the latest update twice now as well once in 64 bit and once in 32bit, nothing seems to cure it.

Pc Intel i5 3ghz, 16 gig ddr3 1600mhz, gigabyte z77 d3h motherboard windows 7 pro 64 bit sp1

Any help is very much appreciated
Kind Regards James Allan

Ps This spiking is so severe that it renders 7.5 useless.

Are you running play 4.xx by any chance? That causes horrendous spikes, more so when the mouse is moved, gfx drivers have had the blame, no fix yet…though have gone back to 7.2 due to spikes like many other here…