I love taking notes by hand for better retention, but (my) longhand is just too slow. It's also an inconvenient format for representing a hierachy or graph of connections. Anyone else into what my high school biology teacher loved referring to as "pseudo-arachnomorphic diagrams" (Mind Maps[1] / Spider Diagrams)? They're still my primary paper-based realtime note taking method. They seemed to get a lot of attention a…
The learning curve is very gentle, you could learn it in a day. Honestly the hardest part is getting used to reading it fluently.
You can also look into various systems of abbreviations developed for telegraph (Evans basic English code), or you could look into using Yublin, which is basically taking all 2-letter combinations and assigning the most common 676 English words to them. Personally I like the idea of Yublin, with the addition of suffixes to modify common words so the word "add" might be "ad" in Yublin, but to make it "addition" you might turn it into "adn" and to further modify it to "additionally" you could write "adnly". This way you get more words out of your limited number of bigrams instead of polluting it with a word plus all it's commonly used variations. Write that shit in Orthic and you'll be flying.
Food for thought.