Spinning Beachball Hangs computer up

I am running Monterey 12.7.4 and my iMac works fine when I first boot up. However about 30 to 45 minutes of use it really slows down and I get the famous beachball. Then if I restart all is good for another 30 to 45 minutes. I talked to an Apple person and their suggestion was reinstall Monterey, which I did and it seems to work for longer periods of time 1 to 2 hrs, but eventually I get the beach ball. Nothing in activity monitor tells me I have something slowing things down. The Apple person said "the newer OS's were really designed for the M chips so the performance on the intel chips suffers." Any thoughts? I hate to reboot all the time.