Hello, I started noticing this issue very recently. I'm running Firefox Quantum (62.0.2 64-Bit) on Mac OS High Sierra (10.13.6). I use Adobe Illustrator for work and more than often need to download .ai files from Firefox (part of how our work interface is set up). Normally, these .ai files open very quickly and load automatically into Illustrator, but now are taking much, much, longer to download, especially since the files are relatively small (for example, 164 kb). I caught the tail end of a download the other day, and for a 164 KB file, it was downloading at a rate of 810 bytes/sec. After a successful download, I notice that my computer will hang, and I will get the spinning wheel. I'm getting the same results with .zip and .pdf files. Image files, however, seem to download normally. The issue seems present in Chrome too, so I'm wondering if it's something with my computer (though my computer was purchased new in April 2018). Speed test is 150 Mbps download/158 upload, so I don't think it's my speed. I run McAfee LiveSafe and MalwareBytes and have found no malware; all the scans check out clean. I also quit both of these programs to see if that would make a difference with the downloading, but it didn't help. I've done the Refresh Firefox feature, cleared my cache, restarted plenty, uninstalled/reinstalled Firefox, but to no avail. I have also restarted Firefox in Safe Mode, and the problem still persisted in Safe Mode. For reference, this link will take you to a download file for a .zip file for a font I needed to download recently (on 1001fonts.com) https://www.1001fonts.com/kg-broken-vessels-sketch-font.html Normally, these font files would take seconds, but this particular one took at least a minute. Thank you for your time.