I'm also suffering from lag. When I test my internet it's very fast. I even restart my machine to make sure nothing is using memory and the browser has only 1 tab. I just played a game where my premoves burned 2-5 seconds each. I premoved the whole game and still lost on time by 3 seconds even though I'm sure I was burning less real time than my opp. It's so brutal... other games the lag is gone and the premoves take 100ms or some very small amount where it's barely a factor.
Why is chess.com so laggy?

I just took advice from someone on here and went to lichess.org. I was able to complete a three minute game with 40 seconds MORE than my opponent before he resigned. in chess.com I will play and I have 0 seconds while my opponents have sometimes over 2 minutes left. Chess.com favors players from certain geographic areas, giving them a MASSIVE advantage. I am unfortunately going to have to avoid chess.com. When I play in person I regularly beat 2000+ ratings but on chess.com I run out of time against 1400's! Chess.com has REALLY gotten worse.
lichess.org is DEFINITELY faster. I am not being paid for this btw...I just took advice from another chess.com user who is disappointed in it's substandard performance. Perhaps they not only prioritize certain geographic areas but also prioritize pay players? I think badly written code and advertisements are possibly to blame as well. Anyhow, I appreciate the advice about lichess.org and would love suggestions about other places to play.
Hopefully chess.com can fix these severe problems.

Its because the Chess.com player pool is insanely big and constantly growing. Not that complicated to fix but ofc requires Chess.com to upgrade their servers and that costs money so.... 😉

My opponent just ran out of time 0.0 on clock, game spiked and I was expecting a win notification as usually. Nope, he received 3.5 seconds back and he did like 6 more moves and only after that he ran out of time for the second time and actually lost. What a game....
Site is basically unplayable now. I lose more games/points due to lag and/or disconnect then playing.

Site is basically unplayable now. I lose more games/points due to lag and/or disconnect then playing.
You might check out the following.
https://support.chess.com/en/articles/8584209-how-do-i-fix-my-disconnect-lag-issues
https://support.chess.com/en/articles/8652402-how-can-i-optimize-my-online-chess-performance
Chess.com is a very laggy site. It wasn't so several years ago. Chess.com has to stop overmodernizing this website.
Site is basically unplayable now. I lose more games/points due to lag and/or disconnect then playing.
You might check out the following.
https://support.chess.com/en/articles/8584209-how-do-i-fix-my-disconnect-lag-issues
https://support.chess.com/en/articles/8652402-how-can-i-optimize-my-online-chess-performance
its a bigger issue for the site lags but others don't. chess.com should do something. Discord is not that laggy even a bit

its a bigger issue for the site lags but others don't. chess.com should do something. Discord is not that laggy even a bit
There are a lot of things that can impact connection quality. Most of those things are outside of the site's control, other than how to deal with lag and disconnects.

I notice this too, on a relatively new laptop. It is only chess.com that is lagging, and it causes Chrome to freeze, meaning that it is not an issue with my WiFi. Checking task manager, the processor is using all of its power. All other sites that I use daily work completely fine. What is wrong?
Site is basically unplayable now. I lose more games/points due to lag and/or disconnect then playing.
You might check out the following.
https://support.chess.com/en/articles/8584209-how-do-i-fix-my-disconnect-lag-issues
https://support.chess.com/en/articles/8652402-how-can-i-optimize-my-online-chess-performance
Tried that...........no difference.
I have never had this problem before, but today lag was so bad!