Memory issue when running Zoom on iMac running Ventura

Two things that stand out for me in your report:

1) You should uninstall "securemac" - third party antivirus are completely useless and can cause performance degradation and other issues.

Effective defenses against malware and other threats

2) You have Chrome and especially its evil "keystone" agents and daemons. While I have no reports of them conflicting with Zoom specifically, they are known to be very poorly programmed, and at times grab the system videotoolbox, killing video and media applications because of it. They could be playing a part here.

I'd start with step 1, and test.

There's another issue that might be significant:

Write speed: 681 MB/s*

Read speed: 2889 MB/s

The HD portion of your Fusion Drive may be failing. It's write speed is lower than it should be.

First thing to do is make sure you have a full and current backup of your Fusion drive with Time Machine or other backup system. If you can get the iMac to the nearest   Apple Genius Bar they'll do a free diagnostic on it to see if that's the case or not.

If the drive is failing you don't need to replace the HD part internally but get an eternal SSD, clone your current system to it with Carbon Copy Cloner and boot and run from the SSD.  

If the hypothesis above is correct I suggest you contact Customer Support as OWC (MacSales.com) and get their recommendation of their several external SSDs based on your iMac year and model, work requirements and budget. OWC is considered by most of the experienced contributors here to be the premier hard ware supplier for Macs. Just some food for thought.

I use Zoom frequently. I am now on Sonoma, but used to use it in Ventura and never experienced this problem.

It is possible that there is a conflict with something else installed on that mac.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

Another observation: you seem to have been upgrading this in place, perhaps coming back from a previous mac, so you have a bunch of old stuff in there that does not work in a current OS (flip4mac, silverlight...).

Often when this happens, the combination of old extensions and daemons at some point causes problems.

Given that you're not encountering similar issues with Zoom on your MacBook Pro with an M1 Pro chip and 32 GB of RAM running Sonoma 14.3.1, it's possible that the problem on your iMac could be related to the operating system. It's not uncommon for certain applications to experience compatibility or performance issues with specific macOS versions.

To address this problem, first, ensure that your iMac's operating system and Zoom application are both up to date. Software updates often include bug fixes and performance improvements that could resolve the issue you're facing.

Additionally, you can try resetting Zoom's settings on your iMac. This can sometimes resolve software-related issues. You can do this by opening Zoom, navigating to the "Zoom" menu in the top-left corner of the screen, selecting "Preferences," and then clicking on the "Advanced" tab. From there, you'll find an option to "Reset all settings to default." After resetting the settings, restart Zoom and see if the problem persists.

If the issue continues, you might consider contacting Zoom Support for further assistance. They may be able to provide more specific steps or insights into why Zoom is behaving this way on your iMac. Additionally, you can reach out to Official Apple Support for help diagnosing and resolving any potential macOS-related issues.