Another many-tabs-open "not-responding" condition

[context]

About 3 months ago, I started having occasional "not responding" conditions with Pale Moon.

As I've continued to monitor these conditions, I'm noticing that what I thought should be dormant tabs are remaining active, at least to some degree.

I routinely will have 20 to 40 tabs open, with some of them displaying resource-intensive sites. A couple that come to mind are Google Maps and Google Images.

Today, I again experienced the condition where PM goes to 50% of CPU use and stays at that level. It doesn't respond to clicks and after a couple of minutes a "not responding" program failure message comes up and the OS shuts down PM.

But here's the new (to me) and strange thing: Upon restarting PM and requesting Restore Previous Session, PM proceeds to properly open all the tabs — but sites like news sites take off playing their videos and loading their excessive content without me ever clicking on any tab. The result is a real traffic jam of activity ... when all I want is to be back where I was (i.e., 40 tabs "open", with the one I selected updated with current content).

Am I totally misunderstanding the preferences setting of "Don't load tabs until selected"? Is the setting ignored when PM restarts? (BTW, after I get rid of the offending tabs, PM runs fine for hours before another condition occurs.)

Thanks in advance for any help.

Regardless of the answer to this particular question, I want to emphasize that something has changed in PM that results in at least one of these major jams for me each day. My browsing hasn't changed from last year ... and last year, these jams didn't occur.

PM 28.5.2 on 64-bit Win7 Pro

[Moonchild]

Unless you want tabs to load all their content when the session is restored (usually not the case if you have many tabs open) you want to keep "Don't load tabs until selected" enabled. Tabs will be restored but will be "suspended" unless you click on them to bring to the foreground.

If this setting is ignored, then you most likely have an extension that overrides normal behavior.

[context]

you most likely have an extension that overrides normal behavior

I don't have many, other than AdBlock Latitude and a couple of theme tools. So, could something as basic as Active Tab More Visible be a problem?

ALSO, are there particular settings in the user.js prefs file that can alter tab behavior? (I've changed a few over the years.)

Thanks for any help.

[Moonchild]

So, could something as basic as Active Tab More Visible be a problem?

Quite possible. Anything that manipulated tabs or tab behavior is a prime suspect

ALSO, are there particular settings in the user.js prefs file that can alter tab behavior?

Of course. Normal users also should not be using a user.js -- it will override whatever settings you make in the normal profile preferences (and could therefore be disabling the option you want). Normal operating procedure for the web browser is to retain settings made by the user in the previous session. user.js is specifically there to override user-made settings and can cause lots of confusion what is actually in effect.