The OOM killer is particularly bad with ZFS since the kernel doesn’t by default (at least on Ubuntu 22.04 and Debian 12 where I use it) see the ZFS as cache and so thinks its out of memory when really ZFS just needs to free up some of its cache, which happens after the OOM killer has already killed my most important VM. So I’m left running swap to avoid the OOM killer going around causing chaos.

I think that also causes issues for roaming profiles and folder redirection. If roaming is turned on then everything in the %appdata%\roaming folder is synced to a server. %AppData%\Local is not. So if your app is using %AppData%\Roaming for temporary data then you are causing a whole bunch on unnecessary IO. Same for using Documents since that if often synced.

If your domain will NEVER send e-mail out, you only really need and SPF record to tell other servers to drop e-mail FROM your domain. Even that’s somewhat optional. If you ever plan on sending ANY outbound (you should at very least for the occasional ticket) then do DKIM, DMARC and SPF. The more of these you do, the less likely e-mails FROM your domain are to be flagged as spam.