Safari is operating slowly on my iMac

iMac 21.5″, macOS 15.7 : Safari operating slowly

Clearing the data websites leave on your Mac (cookies, caches etc.) may help:

In Safari app: Choose Safari > Settings > Privacy > Website Data

When the data shows: you can remove some data selectively, or remove all the data.

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More help if needed:

See Apple support's online trouble-shooting article (link below) for tips:

If Safari doesn’t work as expected on Mac

Eg: says

"If Safari doesn’t load a web page correctly, stops responding, quits unexpectedly or otherwise doesn’t work as expected, these solutions may help".

(See that above linked article for the details.).

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Safari Support website: (info. / support contact options etc.)

https://support.apple.com/safari

have you tried restarting your Mac and updating it to the latest version of macOS

Thank you for letting us know you solved the situation, and how. Cheers :-)