With all the latest jupyter and jupyterlab packages installed and a clean python environment, I can confirm that the jupyterlab UI becomes very slow if Show Contextual Help window is opened.
The issue also depends on the type of text/variable/function one types in the code cell; here are my observations:
- If you are typing in a code cell a function which is already installed, for example, numpy.arange(…), the contextual help shows the corresponding help very quickly and thus no lag.
- However, if you start typing in a code cell an object or variable which contains data, for example, a pandas dataframe say df, then as you type df, contextual help starts to load and show the data within that variable slowly. In addition, if you keep on typing like df.head, then the contextual help changes from the data content to the help contents of the function typed (in this case head()). This makes the whole jupyterlab UI freeze until the help is loaded.