I fixed the Atom Ink issue. Performance for displaying a 100K item tree went from 132 seconds to 216 milliseconds. https://github.com/jasongilman/proto-repl/issues/69#issuecomment-201901991 More changes coming to speed up the entire thing.
I just released Proto REPL 1.1.6 with this performance improvement. It also disables the automatic pretty printing by default for now which temporarily avoids another issue https://github.com/jasongilman/proto-repl/issues/77
Evaluating (range 10000) has gone from about 3.5 seconds to 700 ms.