Recently, the Spyder IDE faced serious typing delay or lag. Basically, after entering something using the keyboard, it takes almost half a second for it to appear on the screen. The issue can also be described as a typing lag in Spyder.
This seems to have been triggered by the installation of Big Sur OS.
Spyder slow on Mac
After intensive googling, we stumbled upon this Github page detailing several possible solutions.
The one that worked for us was installing pyqt and pyqtwebengine. Basically, type the following commands in the terminal:
pip install PyQt5 pip install PyQtWebEngine
The above solution should be very safe since it is just installing Python packages.
The above solution helped to solve the troubling issue of Spyder lagging. Since Spyder uses Qt for its GUI, it is critical to keep the various Qt related packages updated / at the correct version. This may be the reason why installing PyQt5 and PyQtWebEngine helps to remove the lag in Spyder.
Spyder very slow
There seems to be many reasons, other than the above, that can result in Spyder being very slow. One tip that is useful, is never update to the latest version of Spyder, Mac OS, or Anaconda immediately once it is released, unless it is absolutely necessary. Most of the bugs appear in the newest releases, and can cause multiple problems including making Spyder very slow. By updating at a later date, most of the bugs would have been solved by then and it is a much safer approach.
Previously, updating to the latest Spyder 4.1.5 also caused several problems, including lag, slowness or even Spyder simply just crashing.