With a warning that I may have less experience than you, tclfan -- but I liked your question and so tried this test of IceWM mem use.
rendir c:\tce c:tcex // to preserve my regular settings
MD c:\tce // to get a clean empty extension folder
rebooted via CD using 'tinycore base' -- it took 54 sec.
In Control Panel, System Stats, tab 'mem'...
MemTotal 182,240 kB
MemAvailable 144,888 kB //using base flwm
Then after Mounting IceWM only, 1st reboot took 60 sec.
MemAvailabel 133,008 kb // for a loss of 11,880 kb compared to flwm
Same procedure to test Joe's window manager; jwm...
MemAvailable 143,704 kB // for a loss of only 1,184 kB compared to flwm
and jwm adds date and time -- (now if it just shoehorned in one pretty, bolder font to aging eyes
)
So, tried same procedure with jwm-snapshot... gaining larger font, date time & dynamic mem...
MemAvailable 140,024 kB // for a loss of 4,864 kB compared to flwm
For me, still ugly window frames and chintzy impression --
Same procedure for HackedBox...
MemAvailable 143,148 // for a loss of only 1,740 kB compared to flwm
Styles Artwiz and Steelblue have adequate to beautiful graphic refinement, 3d window frames, but with a weak font off a previous century's pre-selectric typewriter.
(Since I like to plant flower beds here, paint white walls and hang art and drapes, I'm stickin' wid' IceWm!)