Mikhail Gorbachev put the full force of his personality on display for the American news media and public last night in a sweeping and energetic performance of nearly two hours at a packed news conference here at the end of his three-day summit with President Reagan.

He showed a grasp of detail on every issue, a sharp contrast to what American audiences have become used to with Reagan. But unlike the ease with which the president deals with controversy, Gorbachev once again flashed the impatience and resentment that surface quickly over some of the demands that Americans make of the Soviet leadership, especially the barrage of human-rights questions that journalists posed.

Gorbachev's stake in a positive outcome of this meeting was very high, and he spoke passionately of how he and his new partner, Ronald Reagan, had made "considerable headway" in talks about strategic nuclear arms and how this had paved the way for a broad range of future agreements.

Yet, between the lines of Gorbachev's positive thinking, it was clear that stalemate rather than progress between the two superpowers was the norm on the tougher bilateral issues. Gorbachev reported little progress in his broad objectives of ending the war in Afghanistan on terms that would let him withdraw gracefully. Nor was there any noticeable progress on two of his most high-profile campaigns: for a ban on chemical weapons and a nuclear test ban.

And yet, in his tour of the horizon of his first visit to the United States, the Soviet leader declared success across the board, brushing adroitly past the thornier issues in the talks on arms control and other areas.

Since closer relations with the United States lie at the center of the foreign policy Gorbachev has fashioned, success in his third summit with Reagan was considered crucial.

Gorbachev appeared eager to portray the U.S.-Soviet relationship as infused with a strong positive impulse. Asked about his relations with Reagan, which have undergone stormy periods, Gorbachev said: "Our dialogue is more businesslike. There is more of a constructive approach, and I'll even venture to say that I think we trust each other more."

Stressing the positive, Gorbachev said that in the negotiations for a proposed 50 percent reduction in strategic, or long-range, nuclear weapons, the superpowers had reached agreements for cuts in sea-launched cruise missiles and for new sublimits on land-based missiles.

Gorbachev also reported that the two sides had agreed to adhere to the 1972 Antiballistic Missile Treaty, adding, "and that includes the process of research, development and, if necessary, tests which are allowed under that treaty."

The Soviet Union has been opposed to testing components of Reagan's Strategic Defense Initiative program, which Soviet officials have argued in the past is prohibited by the ABM Treaty.

On the politically charged subject of Afghanistan, Gorbachev announced that the timetable for Soviet troop withdrawal, a crucial ingredient for efforts to end the 8-year-old military conflict, will be 12 months. U.S. and other outside aid to rebels opposing the Soviet-backed regime ruling Afghanistan and Soviet military aid should end simultaneously with the start of Soviet troop withdrawals, he added.

Gorbachev declined to announce when the Soviet troops will start leaving, however. He also blurred the crucial issue of the nature of the government that will rule in Kabul after the troops have withdrawn, saying that Moscow will not insist that it be pro-Soviet, but that Washington should not insist that it be pro-American.

He said that from the day western aid to rebel forces is ended, Moscow will begin pulling out its troops. But apparently Gorbachev did not obtain an agreement from the Reagan administration to stop supplying aid to Afghan insurgents if Soviet troops withdraw.

During his 72-minute opening statement at the news conference, Gorbachev complained that he is asked too many questions about Soviets forbidden to emigrate or still imprisoned for political offenses. And he flashed into one of the most animated moments of his trip.

"Is that a dialogue?" he asked. "Is that an interview? That's not what the media is for.

"I'm not trying to accuse any of you," Gorbachev added. "I'm just trying to say that the media has to go for some perestroika," too, in a reference to his policy of reconstruction or reform.

Following his expansive opening statement, Gorbachev gave journalists brief and often perfunctory answers to their wide range of questions. Asked whether he or the audience should be disappointed with the results of the summit, he said, "You're pulling me the wrong way. I cannot add anything to what I've said in my introductory remarks."

Gorbachev, who left last night to brief Warsaw Pact allies in East Berlin, also said he will report to the Soviet people when he returns home.