Hey Frank,
I got back into my admin finally.
I had changed this piece of code in preparation for that, and after bouncing around a bit with Query Monitor on, I am no longer seeing those notices.
I don’t expect you to know, but maybe you can point me in the direction of a plugin you know works (an author friend perhaps? :p)…
After accessing myPHPadmin and removing TONS of old wp_options, wp_postmeta, etc AND noticing that my ‘home’ url ended with a ‘/’ (and removing it of course) that’s when I was able to access the admin without 500 errors again…
It was still very slow, but somewhat faster than before. I ended up uninstalling the Query Monitor because I wasn’t seeing anything too interesting anymore, but then I installed WP SERVER STATS.
And now I am seeing the issue I think… Anywhere from 60-90% CPU Load on average.
And when I’m watching the “real time” bar, it spikes randomly from sitting dormant at about 35% to up to 90% again, and that’s just sitting on the dashboard page after logging in.
Crazy stuff, not sure how this is happening but it explains a lot. Memory was never an issue, it’s been a CPU Load issue all along that’s just dragging the admin panel into the ground. Your plugin and Super Cache are keeping the front end of the site like lightning, but loading my own site pages while logged in is terrifyingly slow as well (Super Cache not loading cached pages for logged in users obviously so I’m getting the ‘real’ speed and CPU Load of things when I’m logged in).