You search in this forum or developers devtalk forum for topics related to OpenSubdiv 2.8 implementation or slow animation en viewport in 2.8, for example:
https://blenderartists.org/t/the-2-8x-opensubdiv-implementation-development-thread/1118910
CPU has a lot to do, and Single thread performance is no less important than Multi thread performance. The CPU you chose for the update is good in both cases.
Also with SubSurf and particles it may be that RAM is filled and begins to intensive use virtual memory on disk, so the whole system becomes slow. But you also have plans to increase system RAM.