[Freeswitch-users] Conference vs codec sample rate and CPU

Hi guys, I have a bunch of conferences on my FS. Users are either G.711/8000 or G.722/8000. Conference sample rate is set to 8000. When I switched some users to OPUS instead, the CPU consumption jumped 3-4 times even though the conference rate is still 8000. Is this expected? I was hoping to be able to save some CPU by setting the conference sample rate to auto (so it only used high-quality sampling for users that can support it) but it seems it won't work. Any ideas?