I am doing trades on ehterdelta where the default gas price is 4 Gwei. The network in the last few days is terribly slow I remember 1 week ago I was making trades on 1 Gwei and even 0.1 and the transactions were done within minutes, now with 4 Gwei I have to wait like 20 minutes and sometimes the transactions get canceled. My question is what is the reason for this? Is it temporary or it will be like this for the near future?