suddenly very slow, high cpu for many normal tasks

My Linux Mint Lenovo Thinkpad e14 is unrecognizable after booting today. Many simple tasks take 5+ times longer than they used to, and my CPU is much much higher than it used to be for the same tasks. Examples: tab switcher, right click, opening firefox, thunderbird, sublime, etc. - I ran sudo apt update && sudo apt upgrade *after* this started but it did not help - I've rebooted several times - Yesterday, I installed at least 1 new R packages as root, and accessed a remote HPC cluster for the first time - I booted into Windows 10 (dual boot) and everything seemed fine there, suggesting hardware is OK? ... Not sure if any of that is relevant output of inxi -Fxxxrz:

System:    Kernel: 5.15.0-105-generic x86_64 bits: 64 compiler: N/A Desktop: Cinnamon 4.8.6 wm: muffin 4.8.1 
           dm: LightDM 1.30.0 Distro: Linux Mint 20.1 Ulyssa base: Ubuntu 20.04 focal 
Machine:   Type: Laptop System: LENOVO product: 20TA004HUS v: ThinkPad E14 Gen 2 serial:  Chassis: type: 10 
           serial:  
           Mobo: LENOVO model: 20TA004HUS v: SDK0J40697 WIN serial:  UEFI: LENOVO v: R1EET56W(1.56 ) date: 06/29/2023 
Battery:   ID-1: BAT0 charge: 16.6 Wh condition: 45.8/45.0 Wh (102%) volts: 11.1/11.1 model: LGC 5B10X026 type: Li-poly 
           serial:  status: Discharging cycles: 2794 
CPU:       Topology: Quad Core model: 11th Gen Intel Core i7-1165G7 bits: 64 type: MT MCP arch: Tiger Lake rev: 1 
           L2 cache: 12.0 MiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 44851 
           Speed: 727 MHz min/max: 400/4700 MHz Core speeds (MHz): 1: 492 2: 609 3: 1038 4: 446 5: 652 6: 588 7: 979 8: 667 
Graphics:  Device-1: Intel vendor: Lenovo driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:9a49 
           Display: x11 server: X.Org 1.20.13 driver: modesetting unloaded: fbdev,vesa resolution: 1920x1080~60Hz 
           OpenGL: renderer: Mesa Intel Xe Graphics (TGL GT2) v: 4.6 Mesa 21.2.6 direct render: Yes 
Audio:     Device-1: Intel vendor: Lenovo driver: sof-audio-pci-intel-tgl bus ID: 00:1f.3 chip ID: 8086:a0c8 
           Sound Server: ALSA v: k5.15.0-105-generic 
Network:   Device-1: Intel driver: iwlwifi v: kernel port: 4000 bus ID: 00:14.3 chip ID: 8086:a0f0 
           IF: wlp0s20f3 state: up mac:  
           Device-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Lenovo driver: r8169 v: kernel port: 3000 
           bus ID: 04:00.0 chip ID: 10ec:8168 
           IF: enp4s0 state: down mac:  
Drives:    Local Storage: total: 476.94 GiB used: 295.75 GiB (62.0%) 
           ID-1: /dev/nvme0n1 vendor: Samsung model: MZALQ512HALU-000L1 size: 476.94 GiB speed: 31.6 Gb/s lanes: 4 
           serial:  rev: BL1QFXV7 scheme: GPT 
Partition: ID-1: / size: 342.50 GiB used: 295.71 GiB (86.3%) fs: ext4 dev: /dev/nvme0n1p6 
           ID-2: swap-1 size: 977.0 MiB used: 0 KiB (0.0%) fs: swap dev: /dev/nvme0n1p5 
Sensors:   System Temperatures: cpu: 46.0 C mobo: N/A 
           Fan Speeds (RPM): fan-1: 0 
Repos:     No active apt repos in: /etc/apt/sources.list 
           No active apt repos in: /etc/apt/sources.list.d/additional-repositories.list 
           Active apt repos in: /etc/apt/sources.list.d/deadsnakes-ppa-focal.list 
           1: deb http://ppa.launchpad.net/deadsnakes/ppa/ubuntu  focal main
           Active apt repos in: /etc/apt/sources.list.d/inkscape_dev-stable-focal.list 
           1: deb http://ppa.launchpad.net/inkscape.dev/stable/ubuntu  focal main
           No active apt repos in: /etc/apt/sources.list.d/mendeleydesktop.list 
           Active apt repos in: /etc/apt/sources.list.d/official-package-repositories.list 
           1: deb http://mirror.csclub.uwaterloo.ca/linuxmint-packages  ulyssa main upstream import backport
           2: deb http://mirror.csclub.uwaterloo.ca/ubuntu  focal main restricted universe multiverse
           3: deb http://mirror.csclub.uwaterloo.ca/ubuntu  focal-updates main restricted universe multiverse
           4: deb http://mirror.csclub.uwaterloo.ca/ubuntu  focal-backports main restricted universe multiverse
           5: deb http://security.ubuntu.com/ubuntu/  focal-security main restricted universe multiverse
           6: deb http://archive.canonical.com/ubuntu/  focal partner
           Active apt repos in: /etc/apt/sources.list.d/signal-xenial.list 
           1: deb [arch=amd64 signed-by=/usr/share/keyrings/signal-desktop-keyring.gpg] https://updates.signal.org/desktop/apt  xenial main
           Active apt repos in: /etc/apt/sources.list.d/slack.list 
           1: deb https://packagecloud.io/slacktechnologies/slack/debian/  jessie main
           Active apt repos in: /etc/apt/sources.list.d/sublime-text.list 
           1: deb https://download.sublimetext.com/  apt/stable/
           Active apt repos in: /etc/apt/sources.list.d/ubuntuhandbook1-gimp-focal.list 
           1: deb http://ppa.launchpad.net/ubuntuhandbook1/gimp/ubuntu  focal main
           Active apt repos in: /etc/apt/sources.list.d/zotero.list 
           1: deb [signed-by=/usr/share/keyrings/zotero-archive-keyring.gpg by-hash=force] https://zotero.retorque.re/file/apt-package-archive  ./
           Active apt repos in: /etc/apt/sources.list.d/librewolf.sources 
           1: deb [arch=amd64] https://deb.librewolf.net  focal main
Info:      Processes: 272 Uptime: 27m Memory: 15.32 GiB used: 2.21 GiB (14.4%) Init: systemd v: 245 runlevel: 5 Compilers: 
           gcc: 9.4.0 alt: 9 Shell: bash v: 5.0.17 running in: gnome-terminal inxi: 3.0.38

Any guidance on how to track down the source of this sudden slow-down is appreciated. FYI: cross posted [here](https://forums.linuxmint.com/viewtopic.php?t=418988) **Edit 1** additional info: - cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor | sort -u:

powersave

- lscpu | grep MHz:

CPU MHz:                            2800.000
CPU max MHz:                        4700.0000
CPU min MHz:                        400.0000

While it's in powersave mode, I don't think this is the issue, since the cpu is still ~60% and it does not explain the degree of slowdown.