IN A SUDDEN burst of speed, the federal government has put 155 failed S&Ls out of business in the past three months. That's quite an achievement. Since they were all losing money steadily, that will help to hold down the costs to the taxpayers -- costs that will in any case be enormous.

Equally important, the government has finally demonstrated that it is capable of asserting a measure of control over this epidemic of bankruptcies. For the first time since it began, during this three-month surge of activity the government was selling or liquidating S&Ls faster than they were going bankrupt. There is still a backlog of 247 savings and loan institutions that have failed and are in the government's hands, and S&Ls will continue to fail. But the backlog is now declining. That's real progress.

In the course of extinguishing these 155 S&Ls, the federal government has become the owner of a vast accumulation of their assets -- mostly houses, commercial developments and land on which the loans had gone sour. How much are all these assets worth? Perhaps it's a rough indication of magnitude to say that no one really knows. The federal cleanup squad now has a double job -- not only to shut down the S&Ls that fail but to sell off this mountain of assets. The final cost of the whole disaster will depend heavily on the skill with which the federal managers succeed in putting this property back into private hands. In the long history of American finance, there's nothing that quite approaches this operation in its size and diversity.

A little farther down this road lies a choice that will have to be made by the administration and Congress: Does the country want or need an S&L industry? It was originally set up to provide a separate, protected source of financing for home ownership -- mortgages for home buyers. Along with all the greed and lobbying and corruption, one ingredient of the S&L fiasco has been the frantic efforts of politicians and builders to perpetuate that tradition of preferential lending.

In a time when banks are getting deeply into the business of mortgage lending, the case for a separate system of institutions -- the S&Ls -- is increasingly dubious. The response from the S&Ls' defenders is that banks have many other interests, and will not give precedence to homeowners. But there are many other urgent demands on an inadequate supply of capital in this country, and some of them are crucial to future economic growth. Home buying and real estate development are entitled to equal treatment, but they are not entitled to a priority in the competition for loans.