Ethereum gets expensive and slows up a lot if there is a lot of activity. It's the Grand Old Lady of the DLedgers and so it will take a while for it to catch up to newer more agile chains like EOS, Tron, Universea, Hashgraph or Red Belly.

To see how congested the network is and how much it will cost go to https://ethgasstation.info/. if the standard price is above 25Gwei I usually won't bother to use the network. Ideally I'd like it to be less than 10