iATKOS | United Kingdom

Sorry, bit of a long context but I feel it's necessary.
I got a 17 inch 2011 MBP with the anti-glare display, fully aware of all its flaws, simply because I like the design, plus it's the only 17 inch with a Quad Core CPU which should allow me to daily drive it for non-graphics related tasks (coming from an 11 inch 2015 Air with 8GB of Ram). Specs in the picture (+ Radeon HD 6750M). Need to get all that out of the way, I already know everything there is to know about this machine including all the negatives, I've wanted one since it came out and spent years hunting for one where I live.

The thing is in immaculate condition. No dents or scratches, the battery had like 90 cycles when I got it, the keyboard is still matte meaning it hasn't been typed on too much, it even had the original 750GB hard drive when I got it which leads me to believe I was the first person to be inside it, yesterday when I was installing an SSD (I didn't upgrade the Ram to 16GB yet but I will, I literally just bought the laptop). I didn't take it apart all the way because I ran out of thermal paste (I will order it along with the Ram) but there was barely any dust inside. Either the guy completely refurbished it with new parts (unlikely for the $130 he charged me), or this thing legitimately sat unused for 14 years. There is nothing so far that tells me the GPU will fail immediately (the screen DOES become glitched for about 1 second right before booting into the desktop, but only with OCLP, never with the supported by Apple OS's), and I'm already using gSwitch to force the iGPU only)

Now, the first thing I do after installing a SATA SSD is to install Sequoia with the latest OCLP (2.4.0). Nothing works. The animated background is just white, and it's sluggish. Changing to just an image background + disabling transparency and animations doesn't help. PAINFULLY slow, even AFTER installing the root patches multiple times. The Built-in-Display is detected, so is the GPU, transparency works, etc, but it behaves as if there was no graphics acceleration at all. Just opening Launchpad takes like 5 seconds. Obviously can't even watch a simple video with it, which is basically why I bought it, as a YouTube machine and to keep all my movies in it.

This is extremely weird, because even my 2008 17 MBP with its Core 2 Duo that gets hot enough to cook an egg is snappier running Sequoia. Might not be able to multitask with it, but it's at least usable and it doesn't lag on the desktop running nothing at all. With the same exact SSD (I took it from that one to put in the 2011) and also 4GB of Ram. The difference is huge. Something ain't right.

Then I check the 2011 with Intel Power Gadget. The CPU is running at about 1.00 to 1.20 GHz 90% of the time, always at 100C with the fans in full blast at all times. I saw it boost to 3GHz briefly a couple times but that didn't help the sluggishness at all.

My first thought is Sequoia is too much for it, so I downgrade all the way. And I mean ALL the way. I tested each and every single macOS that would run on this thing, except Mojave I think. Obviously the ones supported by Apple were flawless, and the problems start with the unsupported ones. Strangely, I saw the exact same behavior running Dosdude1's Catalina Patcher. Went through Big Sur, Monterey, Ventura, Sonoma, Sequoia and nothing worked, they all did the same thing. Then I finally settled with Monterey before giving up thinking maybe it would get better if I bought more Ram(?) since I already had an SSD inside.

...Until I thought of downgrading OCLP. So far I had been using only the newest version (again, 2.4.0) with all the systems I tried. As a last resort I went directly back to OCLP 0.6.8 just to ensure it would be something that would play well with Monterey.

It. Just. Werks.
Running perfectly smooth, snappy, fans are quiet, I am even typing all this on it as we speak. The second picture is IPG after it finished Indexing, I guess. (It went from 95C to 55-60C).

This entire post is just to tell you that if your 2011 MacBook Pro is slow with unsupported systems, just downgrade your OCLP. DO NOT use Latest if you're running very old Hardware, or this particular MacBook Pro 8,3 at the very least.
I would like to eventually go back to Sequoia or at least Sonoma: The reason why I went all the way back to such an old OCLP version right away is because I was mentally fatigued and exhausted from juggling multiple OS's to see what works so I didn't test any others, but hopefully someone here can tell us what the correct version of OCLP would be for Sonoma and Sequoia - so far 0.6.8 is playing very well with Monterey. Hell, maybe the devs will see this with some luck. I tried my best to include every detail I could, if that's helpful.