It would probably be your computer or your connection, how does it handle other sites?
HELP NEEDED PLEASE.

Thank you for reply. All other sites are quick/fast ..ok. Seems like some type of delay; but the repeat moves gets you frustrated.... Thought it may be a security/Mac thing? It is really annoying.

Have you cleared your cookies and cache recently? What browser are you using? I highly recommend clearing cookies and cache on a daily basis. Personally I do it every morning before work, I see a significant speed difference when I do so.

3/4 years old? Do you mean 75% of one year old, or 3 or 4 years old?
If you didn't get a fairly top of the line Mac 4 four years ago, it is definitely underpowered by today's standards. The technology moves quickly. The new iMac's (maxed out memory, flash drive) kicks the ass speed wise of an old 6 year old 2x4 core MacPro desktop computer, loaded with memory and a hardware RAID card. And the iMacs have super thin profile and are fan free. , whereas the old Mac Pro desktop is a boat anchor and has multiple fans (CPU fans and case fans).
Do you see any other degradation on your computer? Slowness, network glitches? Maybe you have a virus, malware, disk fragmentation, disc corruption, loaded a bad extension on your computer, etc... Got a lot to check out to narrow down the root cause. Chess.com is snappy and reliable as ever, or more so recently for me, in the USA.
I've been playing several years on this site. The last 2/3 weeks my computer or this chess site has been slower with repeat moves on my part. I move my piece and then it repeats the move. I've tried reloading the site with no solution. Has anyone ever had this problem. I use a Mac desk top 3/4 years old. This delays my play on time . I would greatly appreciate any advise. Thank You! LCviking