After installing SZ, I found that Safari was very slow (lots of spinning beachballs). I unchecked Aggressive Mode in the SZ extension and that solved it.

Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365