Did you check if any driver stalls the deferred procedure calls with DPC latency checker?
Because the temporary freezes could be caused by this.
256 colors isn’t normal.
Did you installed the correct video driver for your video card?
And did you install the correct drivers for your chipset.
And what ASIO driver are you using in Cubase (Devices → VST Audio System)?
Not all 32 bit plugs are running well in Cubase 64 bit, but I understand you bridged them with jBridge. Most of them should work by then. Or you could try adjusting jBridge’s settings per plug-in if a single plug in gives you trouble.
But first things first, your system needs to be healthy and set up correctly.