Debian - Terrible Performance on MacBook Pro. LUKS Related?

Two days ago I did a fresh install of Debian 12 stable + Xfce on my Late 2013 MacBook Pro using LUKS for full-disk encryption. Performance around the OS has been incredibly poor. My CPU is hardly being taxed (50%), and the swap is not/hardly being used. I was using Xubuntu (without encryption) prior to installing Debian and have not installed any software on Debian that I wasn't already using without issue on Xubuntu. Xubuntu was using an earlier version of the kernel if it matters (5.15 iirc, versus 6.1 for Debian). To give you a sense for how bad things are, installing light packages with apt or dpkg takes probably two orders of magnitude more time than it should. Instead of "processing triggers" at the end of an install for a second or two, it's sometimes been taking me a couple of minutes. I just used apt to install htop (a whopping 152 kB) and it took ~15 seconds just to unpack. Programs like Matlab that would open in maybe 10-15 seconds on Xubuntu now take more like 5 minutes. Typically I can copy data to my external hard drive at 75-100 MB/s, but now I'm only getting 5-25 MB/s. The OS and programs are mostly usable but incredibly sluggish. I own a dual-core Celeron Chromebook from 2015 also running Debian 12 + Xfce with full-disk encryption via LUKS and it is *substantially* faster than my MacBook Pro despite the MacBook having a quad-core i7-4750HQ. So, something is clearly very wrong here. The MacBook has "flash storage", which I think is just an SSD. The Chromebook has a M.2 SSD. Download speeds are as fast as ever, so it's not an internet issue. I also confirmed my processor supports AES-NI as called out here . Any ideas for what might be going wrong or how I might troubleshoot this? It would be frustrating to reinstall without encryption only to figure out it was actually a driver or kernel issue, or something, especially since I'm already most of the way set up. So, I figured I'd ask the brain trust before I take any actions. Update: I just opened up a Gamecast on MLB.com and they disabled the real-time player positions with the following message: "This feature has been disabled based on your device's power mode." Looks like I'm using the "schedutil" governor. I doubt the choice of governor is enough to give symptoms like this, but I may fiddle around.