User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 SeaMonkey/2.53.8

Steps to reproduce:

sorry, all other related bugs was closed, see
https://bugzilla.mozilla.org/show_bug.cgi?id=1616551

1. Start Seamonkey browser:
   User agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 SeaMonkey/2.53.8
2. use it for some days

Actual results:

1. the computer become unresponsive (one seamonkey task goes to high CPU use)
2. memory use increase much.
   I noted in the task manager a typical saw tooth when this happen, see attach

Expected results:

memory use should remain low like with 2.49.5

with this version, doing GC/CC/Minimize memory usage in about:memory does not solve the computer freeze, I had to close and restart Seamonkey

Unless a reproducible scenario, logs from about memory before a freeze and detailed system settings can be provided bugs like these are unfixable.

I just restarted SM, after some days I will attach the memory report

I still see:

WARNING: the following values are negative or unreasonably large.
explicit/(18 tiny)/heap-unclassified
This indicates a defect in one or more memory reporters. The invalid values are highlighted.

can this invalidate the report?

today SM is crashed, so I cannot save the memory report. Restarted, wait some days, will see

in this situation, SM respond after 5 seconds. So when

I hover on a link, it become cliccable after 5 seconds
I click on a menù, it open after 5 seconds
rotating the mouse wheel, the page scroll after 5 seconds
...
typing characters in this text box, they appear after 5 seconds

in the task manager I can see the typical saw tooth in memory allocation graph, and SM task is using 100% of a core (12% of the CPU for this computer).

I checked the SM task pass from 5.4 GB allocated RAM to 6.4 GB, and back, continue as so, without doing nothing.
Sorry, for me it's really hard to use SM and save the memory report with these continuous freeze of 5 seconds, I had to restart it.
Please tell me what other information you need to identify the leak

The memory report looks mostly normal.

Wihtout an ad and / or script blocker that is whaty you get theses day after longer use. Junk cummulates but does not look bad here. Also facebook media and google interaction which might cause it. I have seen exessive memory usage with both of them.

please link an ad and a script blocker extention to use and try

See the release notes under Extensions (Add-ons) and Themes
The latest 1.16.x working version of uBlock can be found here. Please install the latest legacy version.
The latest working version of NoScript Classic 5.x can be found here.

NoScript 5.1.9 and uBlock 1.16.4.30 currently. I would start with uBlock.

2.53.9 will have some additional fixes for image memory usage but this is generally a rat race these days.

In Release note, 'Add-Ons' link to https://addons.thunderbird.net/seamonkey/
There, typing 'uBlock' or 'NoScript' in Search box, results nothing, maybe the search engine is broken or the add-ons was removed.
There are 235 pages of add-ons, can you please link the add-ons download page?

https://www.seamonkey-project.org/releases/seamonkey2.53.8.1/

Both are linked in the release notes as stated

The latest 1.16.x working version of uBlock can be found here. Please install the latest legacy version.
https://github.com/gorhill/uBlock-for-firefox-legacy/releases

The latest working version of NoScript Classic 5.x can be found here.
https://noscript.net/getit

found: https://github.com/gorhill/uBlock-for-firefox-legacy/releases

at the same time I updated to 2.53.8.1

uBlock do not solved the memory leak, after 5 minutes of Seamonkey Browser start, it restore prev session, and continue to allocate memories till end, at 8 GB I close it

I made a try, free some memory used for example by a virtual machine, and restart Seamonkey, It's memory increase up to 9.7 GB than stop.
So I tryed to close some tabs, in particular Amanzon and Youtube that are the most hungry, and now Seamonkey use 5 GB.

So better than before, but worse than 2.49
I saved my last used profile with 2.49, but sure, it do not list the current open tabs links.
Is there a method to move the list of current opened web site to the old profile, so I can compare how was the memory allocation of 2.49 to 2.53 ?

Is there a method to move the list of current opened web site to the old profile, so I can compare how was the memory allocation of 2.49 to 2.53 ?

I am not sure if the sessionstore.json is compatible between the two releases. You can try.

Stricktly speaking this is not a leak yet. If a script runs amok It can fill up memory quickly. I have seen this sometimes. Facebook, google and some tracking scripts are the worst offenders. maphub.net also seems to allocate vast amounts of memory for the images

2.53.9 will have some improvements. More to come.