Would you consider a bespoke CMS?
I did 4 times and I'm working on the next one.
I won't write too much to avoid boring you or boring myself, but the first two ones were about: there is no other choice. Learned a lot and boy they were useful. By the 3rd one I built something extremely superior to my previous attempts, fast and adoc to my needs and the company. It was solid, SEO friendly, all that wee need and it worked with high peaks of traffic.
Then the last one... then I noticed my own mistakes and the so many things I could/should have improved. That one still drives my most visited sites.
That one included features I didn't need as a developer but it was more about the clients: multi accounts, multi "databases", etc even a drag and drop module view that was a pain to build.
Over the years I saw others including tech peers battling with WP ha ha falling down, then I converted some of those sites to Drupal because I was not going to be in charge anymore except from my own sites, and I wanted to retain my ownership over the code.
Now that I look at it, my experience is such that I know the code can be better.
If so, why and how would you go about it with optimal efficiency?
reuse code, efficient code, multi purpose code, etc. I keep that in mind and I'm working on my next version but this one will take longer. There are so many things you can do once you have a clear view! and I hate those multi megs solutions when I have fast ones under 3mbs. Not commercial, not for sale etc.