Ignore JonnyLipsham, he thinks you're rendering it in realtime, doesn't have a clue about the real issue.
I also have the same FAST CPU as the OP 8700k overclocked to 5ghz on all six cores, and a 970 evo NVME SSD + 32GB fast ram!
PT's flies by at these tasks in the blink of an eye, takes forever on S1.
I concur with the you OP, the bounce or track transform times in Studio One are abysmal. Slowest in class. I also work with Pro Tools and it's very fast there, because using bounce or commit (esp the latter) does what you say, it intelligently knows to dedicate all CPU to just that track and is often 10x for me with some heavy plugs on the track I'm freezing (track transform) or committed (bouncing to another track with plugs embeeded). On S1 I'm lucky to hit 2x with the exact same project/plugs! THIS is a bug.
If you turn off all plugs then yes, S1 can work fast (10x even with 3 heavy plugs on the track in question) but is not good because you loose the status of you global insert bypass IF you also want to keep the plugs enabled on the track being bounced.
Studio One needs a much more elegant freezing process to, like pro tools, one button on the edit window without having to open up the track inspector, and a greyed out plugs/track that can't be moved so show it's frozen. At the moment, track transform isn't really the same at all as it never leaves a clear state of what you've done, it's essentially a bounce not a 'freeze' even if you CAN retransform back the track shows no indication, and can also be transformed further losing the original state/plugs.
S1 is sorely lacking here and stops it from professional workflow.