Have you tried disabling TPM again? Windows Update recently forced an update for the Realtek audio driver on the XPS 8930 and that update causes the same boot delays you're seeing, regardless of TPM setting. So enabling TPM might just have been coincidental. FWIW, I don't see any boot delays after enabling TPM on my XPS 8930. Look in Device Manager and see what version Realtek driver you have. If it's the problem version 6.0.9205.1, manually set a System Restore point, to be safe. Then use the Roll back driver button in Device Manager to go back to the previously installed Realtek driver version, which might be 6.0.9107.1 which was just before this last one or .8248 which was the one before 9107. After rolling back, reboot a couple of times and see if that solves the problem, while TPM is still enabled. EDIT: After doing the driver roll back, do several full power-off shutdowns, not just Restarts from inside Windows.
I’ve got an XPS 8930 that I wanted to prep for Windows 11. I used the method suggested in another conversation to enable the TPM involving disabling Legacy Option ROM and enabling Secure Boot. It worked fine as far as enabling TPM, but now my boot time on startup has gone from about 15 seconds all the way up to 90 seconds. Has anyone else run into this issue, or is it normal for a longer boot time with TPM enabled? Not happy with this change and considering going back to prior settings and stay with Windows 10 for now. Any ideas of the cause for the slowdown?
XPS 8930, slow boot after enabling TPM