Wavelab 12 using significantly more processing power than 11

hey - i’ve just opened up some older wavelab 11 projects and, while they were using a fair bit of cpu they were working fine, in 12 it’s maxing out and glitching constantly.
same plugins, same project - any way to rectify this as currently 12 is unusable?

many thanks

reducing the buffer size has helped considerably.
any other tips most welcome : )