What's the correct term for ping (connection latency) in Standard Chinese/Cantonese?
Yes, in putonghua，We say "网又卡了， 我ping都500了， 卡死了（damn lagging）， 你卡不？小王怎么一点都不卡呢？”

“Ping” is totally acceptable in Putonghua， just like “windows，NPC，BOSS”， all game players know it， or you can use "延迟”， “我延迟有500了” 。