I will tell you of my very similar experience, most likely nothing to do with your issue but worth posting.
I am running CDVR on Win 11, DVR drive is an external WD 1 terabyte, using default Client buffer aprx 5 min.
I mostly use Firefox browser.
When going to the admin page,using Firefox, sometimes it was very slow to load.
ALL things on Firefox were very slow to load, Gmail, etc. everything.
If I restarted Win 11, stopped and started CDVR for a clean start, all was fine... until it happened again.
I finally discovered what I think is the cause:
IF my wife had left her ONN client running a channel, and had it paused,
then just turned the TV off without pressing HOME or going back to the Guide,
THEN the Slow to load ALL things Firefox issue occurred.
If I went into the admin page (slow to load) STATUS, looked at Disk, Activity it showed
Activity Watching ch6102 FOOD from bath etc, my wife had been gone for hours.... Ahhh-Haaa!
If I went to wife's client, turned on the TV, it went straight to a CDVR channel screen,
it showed her channel frozen with about a 5 minute or so timeline buffer, but not seeming to be running.
Stopping that channel going to the Guide, then HOME and BINGO, all things Firefox were loading normally.
I'm not sure why this had such an influence on Firefox but I'm fairly confident this is the cause
Having a channel paused for an extended period, maybe hours.
Other browsers were not having a Slow to load issue, using Chrome to go to admin page etc was fast as usual.