Obsidian on macOS 26 (Tahoe) currently uses Electron 32.2.5. This is below version 36.9.2 where known Tahoe performance issues (GPU/private API related) were fixed.
This problem has been widely discussed for many Electron-based apps running on Tahoe.
Proposed solution
Update Obsidian to a newer Electron (≥36.9.2) to include these performance and compatibility fixes.
It looks like obsidian will not automatically update the electron version via OTA (not sure if this is on purpose) so I had to reinstall (relatively simple to do) even though my obsidian version was up to date the electron version was not. @WhiteNoise let us know if that’s the intent