Very slow performance on iMac (Retina 5K, 27'', 2019)

Hardware wise.

A Fusion Drive was good in its day for inexpensive addition storage though would be must slower than an all SSD Configuration 

APPLE SSD SM0032L 28.00 GB (Solid State - TRIM: Yes)

HDD ST1000DM003 1.00 TB (Mechanical - 7200 RPM)

8 GB RAM  would the bare minimum to run this machine 

➡️ If you want to extend the useful life of this machine ? ⬅️

Consider having the RAM upGraded by Professional . It can handle up to 128 GB RAM

Get an good External Enclosure  and a compatible SSD drive for the enclosure

Install the operating system on the external drive and make the drive the Startup Drive 

Good starting point would be www.owc.com which may have matching enclosures and SSD drive specific for this iMac 2019 

Software wise 

macOS Sonoma 14.5 (23F79) Current Sonoma is version 14.7.4 

Apple security releases

GlobalProtectExtension - version 5.2.10-6 (Palo Alto Networks - installed 2022-04-25) >> Needs to be updated if available

com.paragon-software.ntfs.loader.plist (Paragon Software GmbH - installed 2023-11-06). >> Needs to be updated if available

Google Chrome (Google LLC - installed 2025-03-25) >>  Known to be resource intensive  and other things 

Consider www.brave.com which is essential Chrome without the overhead of Google 

Application memory error on my MacBook Pro - Apple Community

The only items I notice is you have a Fusion drive and you could use more memory. You only have 8GB, 16 or more would be recommended. Also you could run an external drive off one of your TB ports that would speed things up. I use an NVME drive in a Thunderbolt enclosure which is faster than my internal drive. However, the fact that you noted it took 30m to launch all accessories means something else is wrong. I would start in Disk Utilities and check the drive function. Then restart in safe mode and see if speed changes. If it does it means some software is impacting your speed. I'm sure others will have some comments as well.