Don't have an answer but when checking mesh size vs redraw speed I noticed sometimes the screen refresh would only utilise a single thread when most times it appeared to use multiple. A suggestion is to display cpu usage (eg taskmgr) to confirm all of them are being utilised and just check nothing else is hogging the other cpus. Morphs have a big impact on redraw speed (try exporting the mesh as obj and see the difference) so removing any unused morphs could have benefit. I use the hide function with multiple figures, maybe a script to hide non-selected parts of a figure might help but depends on workflow, having to run a script everytime a new body part is selected might be more pain than the current issue.