In my latest tests, the CPU during a tempo change is over 90% during a tempo change and only 20-30% at other times. Unfortunately, my previous "fixes" (either reducing the Kontakt instances or reducing the size of each instance) don't actually work because a single reduced instance still has the CPU around 85% during a tempo change. So, there actually isn't a workaround because even if I replicate VE Pro instances, the CPU will just jump back to 100%.
I've tried almost everything I can think of, with the exception of reverting back to VE Pro 4.