To note: SM BANK
I definitely saw what I saw, OP, that day.
Today, it is different.
Today, I'm getting prolonged high CPU (perhaps not quite as long duration) even after removing both extensions.
Today, FF 52.6 is likewise doing the same, with all extensions disabled.
At the least,
Safe Browsing is playing into this.
(Browser)
Safe Mode does not mention
Safe Browsing, nevertheless, starting Safe Mode alleviates issues cause by Safe Browsing.
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The other day (on my Win7 computer), with FF 57, running reasonably well, I updated to FF 58, & on startup, I was seeing prolong, seemingly never to end high CPU usage, that being ~25% CPU, 100% of 1 of 4 cores. With no logical reason for it. And I restart, same. And I restart, same. So I dropped back to FF 57, & still, the same.
So then I figure, I'll "gut" the Profile, blanket deleting "crap". So long as it wasn't particularly important to me, so long as I had a pretty good feel that what I was about to delete I could do without, it was gone.
And in that respect, gone were:
(directories) storage, safebrowsing, startupCache, minidumps, offlinecache, gmp, crashes, cache (maybe some others, but that's the general idea)
(I kept chrome & extensions.)
(Profile Folder, files) I probably kept most all of them, of which generally only sessionstore.json are of interest.
Anyhow, with that "fix", that issue was gone in FF 57 & in FF 58.
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So, I guess what I'm saying is there is all kinds of crap that may be in a Profile that could potentially negatively affect what one sees.
That said, definitely odd what I did see in my OP - especially if it were only attributable to a NoScript change (& "change", not necessarily a particular NoScript
version.) (NoScript would be the only extension to update. For whatever reason an extension update [& in that vain, perhaps it need not have been a NoScript update]
may have had some affect, trigger, on what happened.)
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SeaMonkey & FF 52 /safebrowsing/ ZIP'd-up (~10 MB each):
FF:
https://drive.google.com/file/d/1A-OwM_ ... sp=sharing
SM:
https://drive.google.com/file/d/1HkdB3_ ... sp=sharing
Download (either, both), create a new Profile, open browser & observe CPU usage.
Replace existing /safebrowsing/ directory contents with that from the ZIP.
Open browser & observe CPU usage.
Note that in FF, the "main" set of files are dated 1-15-18, with others 12-13-17.
Note that in SM, the "main" set of files are dated 11-30-17.
Don't know why SM in particular are so old.
Seamonkey slow to load home page at start up
[FF52] Why safebrowsing folder contents can cause a big slow down
From the FF zip, deleting the 1-15-2018 files "fixes" things - at least the browser loads normally (quickly).
Alternatively, deleting any 1 of the following (1-15-2018) files allows the browser to load normally (quickly):
goog-phish-shavar.pset, goog-phish-shavar.sbstore
Deleting all the other files, but leaving the above two, results in slow load.