I love the extension jupyterlab-quickopen. It's (potentially) resolves server issues that I opened in jupyterlab repository. jupyterlab/jupyterlab#3246 is resolved by this extension. jupyterlab/jupyterlab#5056 and jupyterlab/jupyterlab#5481 are probably no longer needed with this extension.
However, I do see performance issues when there are lots of files in the JupyterLab work directory. It also significantly increase the launch time of JupyterLab server when there are lots of files.