See this https://en.wikipedia.org/wiki/Simplex_algorithm#Efficiency https://en.wikipedia.org/wiki/Simplex_algorithm#Efficiency. But simplex is still widely used

See this https://en.wikipedia.org/wiki/Simplex_algorithm#Efficiency https://en.wikipedia.org/wiki/Simplex_algorithm#Efficiency. But simplex is still widely used because real problems are usually solved in polynomial time. You have to design your problem to not finish in polynomial time. But I am not a matematician this opinion it just how I understand it.