It’s possible for the customer to do this thru the API, but it is without express warantee. It’s not possible to resize performance servers thru the mycloud control panel, so, to do it you will need to use curl API, or what I like to use, supernova wrapper for nova or nova. It’s quite simple really;

The below example is how to resize a performance server to 4 gigs (this was from 2 gigs)

supernova customer resize --poll uuidgoeshere performance1-4