I think my findings that I separately published in Speeing up VM startups will also be interesting to people here.
The “have minimal RAM to speed-up startup” is because there’s wasteful (cpu-time wise) clearing of already clear VM pages. I filed a ticket: Wasteful memory clearing at start of every (standard) qube kernel · Issue #8228 · QubesOS/qubes-issues · GitHub
Add kernel option init_on_free=off to your vm kernel options with something like this (this rewrites the options, but I imagine nobody has them set nowadays anyway):
qvm-prefs -s YOUR-VM-NAME kernelopts "init_on_free=off"
I measured 3+ seconds savings in the boot time on gen8 i7 cpu using the default 4G maxmem qube. slower CPUs will benefit more than faster ones.
The “don’t include in memory balancing” seems to be related to this:
[ 2.327810] xen:balloon: Waiting for initial ballooning down having finished.
[ 3.058150] xen:balloon: Initial ballooning down finished.
so you basically don’t load this balloon driver and get the savings from its init. Somebody could look into what the init does and actually optimize it I guess. Again slower CPUs benefit more here. but other factors seem to have big impact too. free xen ram?
[ 1.309210] xen:balloon: Waiting for initial ballooning down having finished.
[ 7.153167] xen:balloon: Initial ballooning down finished.