The same with other wallets the transactions are very slow. The grounds that you mentioned about ETH transactions is right. Theres a heavy traffic in the network pending a lot of transactions unconfirmed. But I guess one of the biggest ground of the current situation is the Cryptokitties. Ive read an article about it and it says that Its making the network clogged due to heavy transactions from buying to selling of the virtual pet. I dont if this is true but it has point.