cubase 8 performance issues

Hi, I noticed when loading a 7.5 project in cubase 8 that the performance is worse in cubase 8. The project has a few vsti’s (halion, ez drummer) Especially the cpu meter spikes all the time and the disc cache load is constantly in the red, whereas in cubase 7.5 its all fine.
I allready disabled hyperthreading in bios. This is a i5 system with windows 8.1 and 3 gig ram.
Regards Erik

Though not related to your issue, I thought you might like to know that the i5 does not support hyperthreading so I think turning it off in BIOS is moot.

Best, Ted

You are running a very small amount of ram. If you are running 64bit it is not enough. Probably not enough for 32bit.
8 does seem to use more memory.