I'm subscribing SONAR since August. 4 months with Sonar, I can't say it's perfect, but I'm happy with it.
I'm working with a laptop which has i7-8750H CPU and 20GB(4+16) RAM. not too bad but little hard for heavy projects like 100+ track mixing, Spitfire BBCSO pro, etc...
Until October, I said "Sonar's optimization is slightly better than CbB, but Sonar itself became heavier and unstable yet... so it's same!" For my laptop, I felt some improvements in plugin optimization on heavy mixing projects(+ showing audio processing load for each plugin was also helpful), but it was subtle... so I didn't feel "better" on heavy projects.
but after November update, I would say "Sonar's optimization became surprisingly better than CbB!". CPU load, stability, almost everything was better, both on heavy and light projects. on CbB, I couldn't run huge mixing project with 100 plugins without freezing, even on 2048 buffer size. But on Sonar after November update, I can run same project on 128 buffer size, without freezing. Really!
I'm really impressed. I've never seen "better optimization" like this anywhere...