7750 performance throttled

I have set all power and performance settings to maximum in the BIOS, Windows, and nVidia settings. However, the system generally operates as if in throttled or power saving mode. I know this because there is a lag with highlighting UI items when I roll the mouse over them, and Adobe Premiere drops frames during playback, even at lowest quality settings.

But, I discovered a work-around. If I reboot and enter the BIOS, then just exit the BIOS without changing anything, the resulting reboot will force the system to honour the maximum performance settings I've chosen. So for the remainder of that session, the UI has no lag and Premiere doesn't drop a single frame, even at highest quality settings.

Then, the next time I reboot (or cold boot), I'm back to square one with throttled performance and have to perform the work-around again.

I have contacted DELL support about this and their solution is to send the laptop back for a motherboard and RAM replacement. But that is just not practicable, as this computer is critical to performing my work duties (video editing), so I'll be unemployed without it, and will lose clients for failing to deliver.

I'm hoping someone here may have some clues around how to fix this issue, so that I don't have to wait weeks for a hardware replacement.

Processor - Intel Core i9-10885H CPU @ 2.40GHz
RAM - 128 GB
Windows 10 Pro 21H1 build 19043.1110
Experience Windows Feature Experience Pack 120.2212.3530.0