I have a fairly powerful Windows 10 machine with multiple SATA SSDs, Core i7-3770K @3.90 GHz and 32 GB RAM. GPU is a GTX 950 powering three 4K monitors at 200% dpi setting.
However, I can basically watch the Windows 10 GUI draw its windows for about half a second, for example, when opening Windows Explorer. Also, simply switching between windows with Alt-Tab is not instantaneous, but takes like 200ms or so until the foremost window is drawn or shown completely.
What components are primarily responsible for drawing the GUI?
CPU? RAM? Graphics card only?
For an upgrade to be worth it, the GUI should be drawn at least twice or several times as fast as it is drawn now.
There are some related questions below, where it seems that the problem partially is due to leaking handles (particularly GDI handles), and due to a setting called Control Flow Guard:
Windows GUI drawing slows down with uptime
Windows 10 - windows open slow, GUI draw slows down with heavy multitasking - but why?
Stuttering tweaks (for other unfortunate 1809 users)
I have frequently noticed the UltraSearch program in the above list causing trouble, as it sometimes automatically gets active in the background when other programs put heavy load on the system. As can be seen above, it has a lot of GDI handles (in the form of bitmaps).