Martin, Steve,
Sorry for bringing up the initial question.
TL;DR
So you both got me to pondering KDE/Plasma Desktop loads etc, etc, etc.
I remembered I had an old lenovo thinkcentre M-93 that I had installed MX linux on for the wife sometime back. (she likes her laptop instead)
I also installed plasma desktop 5.2xxx at the time. So I pulled it out for some experiments. Updated and off to test.
Here are some specs. Attached is the whole machine specs as a file for reference.
*******************************************************************************************
System:
Kernel: 6.1.0-21-amd64 [6.1.90-1] arch: x86_64 bits: 64 compiler: gcc v: 12.2.0
parameters: BOOT_IMAGE=/vmlinuz-6.1.0-21-amd64 root=UUID=<filter> ro quiet splash
Desktop: KDE Plasma v: 5.27.5 tk: Qt v: 5.15.8 wm: kwin_x11 vt: 7 dm: LightDM v: 1.26.0
Distro: MX-23.3_x64 Libretto May 19 2024 base: Debian GNU/Linux 12 (bookworm)
Machine:
Type: Desktop System: LENOVO product: 10AB000KUS v: Lenovo Product serial: <superuser required>
Mobo: LENOVO model: SHARKBAY v: SDK0K17763 WIN 1801925231317 serial: <superuser required>
BIOS: LENOVO v: FBKTCCAUS date: 11/21/2016
CPU: Info: model: Intel Core i5-4570T bits: 64 type: MT MCP arch: Haswell gen: core 4 level: v3
*************************************************************************
At idle no apps running cpu = 2-3%
Add firefox no browsing cpu = 6-8%
Add 2 different open webpages = 11-13%
Add Libreoffice writer and start word processing cpu = 2%
Open second firefox browser and stream 1 youtube video cpu = 28-32%
Stream 2 youtube videos at same time cpu = 30-45%
Add Thunderbird cpu = 13-27%
Idling with apps open cpu = 2-5%

This is respective of my personal useage.
So several things I noticed with this build, although a lot of K-apps are installed:

- Akonadi is not installed
- Nepomuk not installed
- Baloo is not installed
- Kmail works without Akonadi or pulling Akonadi in. I started it but didn't set it up as I normally just use thunderbird
- cpu useage isn't necessarily additive as more apps are opened.

So maybe they have changed a few things since I used it last? I don't know how it is all incorporated but it is similar to Void and Devuan only in the fact that systemd is not default init.
So a possible low resource hungry desktop for those who like KDE?
73
CharlesSystem:

  Kernel: 6.1.0-21-amd64 [6.1.90-1] arch: x86_64 bits: 64 compiler: gcc v: 12.2.0
    parameters: BOOT_IMAGE=/vmlinuz-6.1.0-21-amd64 root=UUID=<filter> ro quiet splash
  Desktop: KDE Plasma v: 5.27.5 tk: Qt v: 5.15.8 wm: kwin_x11 vt: 7 dm: LightDM v: 1.26.0
    Distro: MX-23.3_x64 Libretto May 19 2024 base: Debian GNU/Linux 12 (bookworm)
Machine:
  Type: Desktop System: LENOVO product: 10AB000KUS v: Lenovo Product serial: <superuser required>
  Mobo: LENOVO model: SHARKBAY v: SDK0K17763 WIN 1801925231317 serial: <superuser required>
    BIOS: LENOVO v: FBKTCCAUS date: 11/21/2016
CPU:
  Info: model: Intel Core i5-4570T bits: 64 type: MT MCP arch: Haswell gen: core 4 level: v3
    note: check built: 2013-15 process: Intel 22nm family: 6 model-id: 0x3C (60) stepping: 3
    microcode: 0x28
  Topology: cpus: 1x cores: 2 tpc: 2 threads: 4 smt: enabled cache: L1: 128 KiB
    desc: d-2x32 KiB; i-2x32 KiB L2: 512 KiB desc: 2x256 KiB L3: 4 MiB desc: 1x4 MiB
  Speed (MHz): avg: 913 high: 1252 min/max: 800/3600 scaling: driver: intel_cpufreq
    governor: ondemand cores: 1: 800 2: 800 3: 1252 4: 800 bogomips: 23148
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
  Vulnerabilities:
  Type: gather_data_sampling status: Not affected
  Type: itlb_multihit status: KVM: VMX disabled
  Type: l1tf mitigation: PTE Inversion; VMX: conditional cache flushes, SMT vulnerable
  Type: mds mitigation: Clear CPU buffers; SMT vulnerable
  Type: meltdown mitigation: PTI
  Type: mmio_stale_data status: Unknown: No mitigations
  Type: reg_file_data_sampling status: Not affected
  Type: retbleed status: Not affected
  Type: spec_rstack_overflow status: Not affected
  Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via prctl
  Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer sanitization
  Type: spectre_v2 mitigation: Retpolines; IBPB: conditional; IBRS_FW; STIBP: conditional; RSB
    filling; PBRSB-eIBRS: Not affected; BHI: Not affected
  Type: srbds mitigation: Microcode
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics vendor: Lenovo
    driver: i915 v: kernel arch: Gen-7.5 process: Intel 22nm built: 2013 ports: active: HDMI-A-1
    empty: DP-1, DP-2, HDMI-A-2, HDMI-A-3, VGA-1 bus-ID: 00:02.0 chip-ID: 8086:0412 class-ID: 0300
  Display: x11 server: X.Org v: 1.21.1.7 compositor: kwin_x11 driver: X: loaded: modesetting
    unloaded: fbdev,vesa dri: crocus gpu: i915 display-ID: :0 screens: 1
  Screen-1: 0 s-res: 1360x768 s-dpi: 96 s-size: 359x203mm (14.13x7.99") s-diag: 412mm (16.24")
  Monitor-1: HDMI-A-1 mapped: HDMI-1 model: NS-29LD120A13 serial: <filter> built: 2012
    res: 1360x768 hz: 60 dpi: 49 gamma: 1.2 size: 708x398mm (27.87x15.67") diag: 726mm (28.6")
    ratio: 16:9, 15:9 modes: max: 1360x768 min: 720x400
  API: OpenGL v: 4.6 Mesa 22.3.6 renderer: Mesa Intel HD Graphics 4600 (HSW GT2)
    direct-render: Yes
Audio:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor HD Audio vendor: Lenovo
    driver: snd_hda_intel v: kernel bus-ID: 00:03.0 chip-ID: 8086:0c0c class-ID: 0403
  Device-2: Intel 8 Series/C220 Series High Definition Audio vendor: Lenovo 8
    driver: snd_hda_intel v: kernel bus-ID: 00:1b.0 chip-ID: 8086:8c20 class-ID: 0403
  API: ALSA v: k6.1.0-21-amd64 status: kernel-api tools: alsamixer,amixer
  Server-1: PipeWire v: 1.0.0 status: active with: 1: pipewire-pulse status: active
    2: wireplumber status: active 3: pipewire-alsa type: plugin 4: pw-jack type: plugin
    tools: pactl,pw-cat,pw-cli,wpctl
Network:
  Device-1: Intel Ethernet I217-LM vendor: Lenovo driver: e1000e v: kernel port: f080
    bus-ID: 00:19.0 chip-ID: 8086:153a class-ID: 0200
  IF: eth0 state: up speed: 1000 Mbps duplex: full mac: <filter>
  Device-2: Intel Centrino Wireless-N 105 driver: iwlwifi v: kernel modules: wl pcie: gen: 1
    speed: 2.5 GT/s lanes: 1 bus-ID: 02:00.0 chip-ID: 8086:0895 class-ID: 0280
  IF: wlan0 state: down mac: <filter>
Drives:
  Local Storage: total: 59.63 GiB used: 26.49 GiB (44.4%)
  SMART Message: Unable to run smartctl. Root privileges required.
  ID-1: /dev/sda maj-min: 8:0 vendor: A-Data model: SP600 size: 59.63 GiB block-size:
    physical: 512 B logical: 512 B speed: 6.0 Gb/s type: SSD serial: <filter> rev: 2.5 scheme: GPT
Partition:
  ID-1: / raw-size: 58.61 GiB size: 57.39 GiB (97.92%) used: 26.3 GiB (45.8%) fs: ext4
    dev: /dev/dm-0 maj-min: 253:0 mapped: luks-<filter>
  ID-2: /boot raw-size: 1024 MiB size: 973.4 MiB (95.06%) used: 191.9 MiB (19.7%) fs: ext4
    dev: /dev/sda2 maj-min: 8:2
Swap:
  Kernel: swappiness: 15 (default 60) cache-pressure: 100 (default)
  ID-1: swap-1 type: file size: 4 GiB used: 380 KiB (0.0%) priority: -2 file: /swap/swap
Sensors:
  System Temperatures: cpu: 49.0 C mobo: N/A
  Fan Speeds (RPM): N/A
Repos:
  Packages: pm: dpkg pkgs: 2743 libs: 1435 tools: apt,apt-get,aptitude,nala,synaptic pm: rpm
    pkgs: 0 pm: flatpak pkgs: 0
  No active apt repos in: /etc/apt/sources.list
  Active apt repos in: /etc/apt/sources.list.d/debian-stable-updates.list
    1: deb http://deb.debian.org/debian bookworm-updates main contrib non-free non-free-firmware
  Active apt repos in: /etc/apt/sources.list.d/debian.list
    1: deb http://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
    2: deb http://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware
  Active apt repos in: /etc/apt/sources.list.d/mx.list
    1: deb http://la.mxrepo.com/mx/repo/ bookworm main non-free
Info:
  Processes: 248 Uptime: 4d 22h 45m wakeups: 5 Memory: 15.51 GiB used: 3.43 GiB (22.1%)
  Init: SysVinit v: 3.06 runlevel: 5 default: graphical tool: systemctl Compilers: gcc: 12.2.0
  alt: 12 Client: shell wrapper v: 5.2.15-release inxi: 3.3.26
Boot Mode: BIOS (legacy, CSM, MBR)