I'm on a custom build for gaming (ryzen 1600, 16gb ram, ssd) and routinely I will click the start menu and it will flash open, only to close and the computer will churn before it opens again. I think it's crashing periodically and restarting itself.
Pretty bare install. Chrome and Steam are the only programs running most of the time. I disabled cortana and one drive, though.
I have a similar build as you: 16gb ram, ssd, intel onboard graphics and I have the same issue (Cortana is also disabled for me as well as OneDrive). I didn't start noticing it until a few months ago at most, the menu used to be much more responsive. Perhaps a recent(ish) update broke it?
Acer intel i7 2.50ghz ddr 8gb here, no ssd; the menu opens in about 0.02 seconds. OneDrive uninstalled (not disabled); I don't know about Cortana (haven't seen it anywhere so it doesn't bother me)
Pretty bare install. Chrome and Steam are the only programs running most of the time. I disabled cortana and one drive, though.