hi there.

from top of my head..

try unstalling display drivers using ddu and make a 'clean' re-install. there is always some gunk left from previous drivers...

https://www.wagnardsoft.com/content/display-driver-uninstaller-ddu-v18036-released


is vertical sync on or off? nvidia control panel, 3d settings..sometimes this could produce hiccups by capping the refresh rate.

i noticed that your display is running @75hz. just to rule things out, try setting your display rate to 60 hz and check if there are any changes. sometimes helper apps like g-sync will kick in and that could cause some lags.

try putting it through some benchmark like 3dmark 11, there might be some memory problems after all.

https://benchmarks.ul.com/legacy-benchmarks

it's legacy, but should work fine.

best,
marco