Why is this happening? (Lag so bad I can't play games off HDD)

[xretrogamedevx]

I'm getting horrible lag spikes that makes the system unplayable.

I bought Mechwarrior. It plays fine off the disc. Zero problems. When I load it onto the HDD it is unplayable. It's the same with any game I load onto the HDD.

Here is an example of the booting sequence into Mechwarrior, both with and without lag.

Lagging boot: https://streamable.com/yohvt8
Normal boot: https://streamable.com/71a6ne

The lag goes on throughout the game, particularly when heavy combat is involved. Halo is even worse. You can see from just the boot logo that the FPS is like 10. Why does this happen?

I even noticed that when shutting the system completely off and powering it back on, the green xbox animation will lag at times. Watch the very end where it begins to stutter. Sometimes, however, it doesn't stutter at all.

Lagging: https://streamable.com/vdoktf
Normal: https://streamable.com/5220rt

I read that the green Xbox animation at the very beginning is algorithmically driven (not off HDD or ROM), so if it is lagging what does that say about the xbox? Is it a cpu/gpu thing?

After spending a few hundred $ getting this system up and running I couldn't be any more disappointed.

Current specs:Xbox 1.62TB Seagate Barracuda: https://www.amazon.com/gp/product/B07H2 ... UTF8&psc=1
StarTech IDE/SATA adapter: https://www.amazon.com/gp/product/B00EO ... UTF8&psc=1
24" 40-pin 80-Wire Ribbon Cable: https://www.ebay.com/itm/274553744014

Things I've tried:

New 40 pin cable

New HDD

New SATA/IDE Adapter

Putting old IDE HDD back in via 40 pin able (works with much less lag, but still noticeable)

I'm at a loss and any/all help would be most welcome.

Thank you,

-R