Coinbase used to go down during high price volatility or during huge pump & dumps and many accuse them for dumping their holding at users buy order during those lag period.
They are one of the biggest bitcoin exchanger so having a high traffic during huge price movements in normal but they should add enough resources to handle such high traffic.
Yea, imagine what will happen with other crypto , when all this newbies start to undestand that coins with low cup can make more higher moves than ETH or LTC. Low capitalization => higher the potential.