Hi, Rudyspilot2, thanks for posting your question here
I wouldn't take it in to the Geek Squad as I don't know if they are an Apple Authorized Service Provider or not, and that I could trust them to work on any Mac, let alone my Mac. I (and we) will do what we can to help you out. that's why I'm here, to ask questions, get answers and help, and occasionally help other fellow Mac users out..
First off, we'll need some basic info about your iMac, which you can find under "About this Mac" which is below the large Apple icon on the top left of your screen. What year was it made, how much RAM do you have installed, and maybe the size of your hard drive/SSD and if you have a hard drive installed or an SSD ?? ...Please do NOT post your serial number here as it can get you into big trouble.... That being said, have you tried the most basic stuff ?
a) reset smc/pmu and zap pram on startup 4 times
as per this link: https://www.macworld.com/article/224955/how-to-reset-a-macs-nvram-pram-and-smc.html
b) have you tried starting up in Safe Mode and seeing if your iMac gets a bit faster/works a bit better. You can do that by shutting it down and restarting, holding down the "Shift" key on your keyboard until you see "Safe mode" on your screen, then you can let go of the key....
c) If a) didn't do much and b) didn't do much, then it's probably not a software/application problem......
you could also download (and run) a copy of EtreCheck which should help you better pinpoint where you're having a problem...
I don't know anything about your iMac, apart from that you have one, it's running Mac OS 12.5, and that's it.... so you'll have to fill us in on some details, come up with a few missing pieces of the puzzle, so to say.... right now, I have very little to go on, so I can only give you general help.... the rest is up to you
John B