I’m trying to change patches of a vsti at various points in a track using only one instance of the instrument and only one track while recording the changes and have the changes recalled on play back. ( for example… for an intro play a sound and go into a verse and have the same vsti play a different sound. Is it possible seems so if only in my head.
Sure just make sure you actually record (or hand edit in) the Program Changes on the Track. There is a section in Preferences where you can set types of MIDI Messages to filter out of your inputs so can can have it for example ignore Aftertouch. Make sure you aren’t filtering out the Program Change messages there.
That said why do you want to do it this way? Most VSTi’s will not switch Programs immediately so you will need a gap in the music while the change occurs. The easier thing if the VSTi supports multiple MIDI Channels (e.g. Halion, Kontakt, etc.) is to set the different sounds onto different MIDI Channels.
Thanks for the response. I’m experimenting and I thought I might save some resources as I only wanted to use one patch for four beats and then change the patch for the rest of the song. With 10.5 I’m experiencing CPU spikes. Every little bit helps.
You are probably better off using your time and energy to figure out what is actually causing the spikes rather than trying to come up with an ineffective workaround. 
I was about to say this exact same thing earlier this day but didn’t have the time to respond. 
Why would you go trough all the hassle of trying to do a program changes on the same instance if you can just create another instrument track? Because I’ve tried it in the past and it’s a really ugly solution! A Vsti is not an external synth that usually can switch from one patch to another in a slit second. It can only work if you have like a bar in between or so? But then it can also interrupt playback because it imposes strain on the audio system. So in general not a good idea! You can only safely do this with multitimbral vsti’s like Halion SE using different midi channels on preloaded patches.
Like raino says. If you want to investigate this because you have performance issues with Cubase it will only give you more headache. So put your energy into finding the issue why you can’t have another track present using the same Vsti with another patch?
Thanks for the info. Mostly just curious if it could or would work. As for the spikes just waiting for Stienberg update… normal to have bugs in early vs.
Yes, in very early versions maybe? But not normal to have issues with this nowadays? Maybe it’s an issue with your computer? What version of Cubase are you on? And what kind of computer are you using? OS, Processor, HD, SSD…?