Of course! - Why, don't you like progress?
What's the pattern of the speed decrease, always, or only sometimes?
When it seems to be slow for some time, do a download speed test to see if that's the problem.
Or/and, check your computer's performance at the time, with Task Manager. Go to the Performance
tab and look at what the different sub-systems are doing, like CPU, Ethernet, Wi-Fi... Glance at the
Processes tab and see if there's a full-blown security scan in progress.
You could do the like when using Chrome, too.
Check also for recently installed add-ons and check if any have got "issues" since the last FFox update.
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