G-Sync Monitor, editor drops FPS to about ~20-30 FPS when hover mouse over editor UI

Editor starts and runs at high FPS (scene performance bound) in G-Sync Dell Monitor (144Hz max) But drops to around 30FPS or lower when I hover my mouse hovers or passed over any UI in editor that responds to hover events - and stay low. If I switch to desktop, and back to editor, the FPS goes up again, but repeating the steps above, it drops down again.

I have another monitor setup that is a regular 60Hz, when moving the editor to this monitor it reports high frame-rate without any dropping to lower frame-rate issues as described above.

My system is Windows 10, 32 GB ram, Nvidia 1080 graphics card.

The monitor model in question is:
DELL S2716DG 27" Gaming Monitor with WQHD 2560 x 1440 Resolution 144 Hz Refresh Rate and NVIDIA G-Sync 16:9 TN Panel

Hello,

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Thanks