i installed it now (v0.31.8) via pip on centos7 with python 3.6. Switching to a notebook tab takes about two seconds (notebook has 45 python code cells), saving a texteditor with python code in it takes about 1 second. Chrome Version 63.0.3239.132 on macosx (15" macbook pro). "regular" jupyter notebook is instant on both things.
There are definitely more optimizations planned in the future. The optimizations that happened in the last few weeks took it down from tens of seconds to open and deal with large notebooks.