Scenarios
1) The software started to lag after intense use for hours.
2) The software started to lag when idled for a few hours. (FYI, I don't turn off my PC at night)

Problems
1) The software became less responsive, pausing seconds when navigating each function in the menu bar and adjusting the gizmo.
2) High idling FPS, 95-392 FPS

Resolution
1) Required to restart iClone.
2) Resolution to problem #2: Set end frame and disabling looping could resolve high idling FPS. The idling FPS could stay at 0.

iClone setting:
Display quality: quick mode
Smooth mesh: original
Rigid body/soft cloth: off
GI: off
Quick thumbnail generation: enable

PC Specs:
i9-10900KF
64g ram
2T NVMe M.2 SSD
RTX 3090

Suggestion:
Allow adjusting the gizmo's size and opacity.