"DXGI Swapchain" halves framerate

I wanted to play Minecraft in borderless windowed while keeping G-Sync active, one trick I'm aware of is using the "DXGI Swapchain" feature in Nvidia Control Panel. For some reason when I do this in Minecraft, it nearly halves my fps - from about 220 fps with Iris and Complementary Reimagined to about 130-140. Is this a known issue? Any known workarounds for this?
For the record, I do this in a few other games too, and Minecraft is the only one experiencing this. Testing on NeoForge 1.21.1, Iris 1.8.6. Windows 11 24H2, latest Nvidia drivers.
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