Wendy's International ( WEN), reaching a detente with activist investor Nelson Peltz, said it plans to explore alternatives for its Baja Fresh Mexican chain and speed up the spinoff of the Tim Hortons doughnut chain.

As part of an agreement with Peltz's Trian Partners fund and Sandell Asset Management, the restaurant operator also agreed to add three of Trian's nominees to its board, boosting its number of directors to 15 from 12. The directors -- Jerry Levin, Peter Rothschild, and Stuart Oran -- will join the board Monday.

Wendy's, which has been facing sharp criticism from Peltz as it grapples with declining sales and heavy competition, said Trian and Sandell agreed to vote their shares in favor of the company's board nominees at its April annual meeting. The company said the firms also made "certain other commitments," but didn't provide specifics.

Wendy's now plans to complete the initial public offering of Tim Hortons, as well as its subsequent complete spinoff, no later than Dec. 31. Previously, the company said it would hold the IPO in late March, then spin off the chain within nine to 18 months after the offering.

The company also pledged to look at options to return excess cash to shareholders following the Tim Hortons IPO, including share repurchases and dividends.

Peltz, a billionaire investor whose Trian fund recently acquired about 5.5% of Wendy's, in December called for the complete spinoff of Tim Hortons as soon as possible. He also called for a spinoff of Baja Fresh.

"We are excited that the new directors will work with the board to further enhance shareholder value at Wendy's," said Peltz in a press release. "We are now highly supportive of Wendy's management team and their initiatives, and we believe that these new board members will contribute to Wendy's plan to improve its profitability."