After five weeks of often-tedious testimony on the tangled affairs of Sen. Herman E. Talmadge (D-Ga.), an exasperated Sen. Adlai E. Stevenson (D-Ill.) yesterday ordered Talmadge's attorneys to step up their pace or face sanctions by the Senate Ethics Committee.

Stevenson, who chairs the Senate Select Committee on Ethics, which is looking into allegations of financial misconduct against Talmadge, interrupted yesterday's proceedings to rule on the relevancy of questions by Talmadge's lawyer, Ronald Wertheim.

"Whether it's relevant or not won't itself be very relevant soon," said Stevenson in a weary voice. "We'll all be sound alseep.

"Frankly, Mr. Wertheim," Stevenson said, "I don't think you're doing your cause any good."

Wertheim, who had been questioning Daniel Minchew, the chief witness against Talmadge, about Minchew's complicated finances over the last 13 years, looked dismayed, and assured Stevenson he would proceed quickly.

The exchange was the second in two days between committee members and Talmadge's attorneys, who have been trying for the last week to paint a portrait of Minchew as a liar, cheat and all-around deceiver.

On Wednesday Stevenson told Talmadge's chief attorney, "If I seem impatient I am impatient, and so are five other members of this committee."

The hearings, which committee officials originally predicted would last two weeks, will enter their sixth week when they resume Monday. All six Ethics Committee members and Talmadge have been in attendance throughout.

Stevenson did not specify what type of sanction the committee might employ against Talmadge or his attorneys if the current pace dragged on. But he warned that unless the senator's attorneys stuck more closely to the committee's rules on evidence and did not stop raising irrelevant subjects, they could trigger committee action "we had hoped to avoid."

Talmadge offered a rebuttal to the committee chairman during a brief news conference outside the hearing room. He said his attorneys were "testing" Minchew's credibility with their questions.

"We've demonstrated every day that he's been on the stand that he's a liar and a cheat," Talmadge said.

During his testimony yesterday, Minchew acknowledged that he failed to tell Matthew Nimetz, an old friend and coinvestor, that he sold their joint 1971 real estate purchase in 1974 and pocketed the proceeds of the sale.

Wertheim, a State Department attorney, said Nimetz, learned of the sale only two weeks ago when Talmadge's attorney told him about it.

Minchew said his attorney and Nimetz's lawyer had been working on a settlement of Nimetz's $5,000 investment in the property. He said he had paid Nimetz $12,000 over the years since the investment was made. Minchew had also put up $5,000.

Throughout the questioning yesterday, Wertheim sought to show that Minchew had overstated in testimony to the committee his net worth when he came to work for Talmadge in 1971. That was done, Wertheim indicated, to shield profits Minchew made while employed by Talmadge from 1971 to 1974.

In executive-session testimony last October, Minchew said his net worth when he got the job with Talmadge was between $500,000 and $600,000. But yesterday he said he actually had a net worth of $40,800 at the start of his employment with the senator. A financial statement he filed just before leaving Talmadge in 1974 showed his net worth at $239,000, Wertheim said.

Minchew has claimed that he and Talmadge shared the proceeds from a secret bank account containing $39,000 in illegal Senate reimbursements and mostly unreported campaign contributions. Talmadge has denied the allegation, and has said Minchew embezzled the cash on his own.